Elements of a DDC System <4>

Multiple Dial LAN Support
In a system’s architecture, the local sites have the ability to call an alternate communication interface, if the primary is not available (Figure 17).

One-Way Dial System Architecture
One-way dial systems, Figure 18, are typically used to enable system owners to access their systems from a remote location, such as their home. It is used where auto-dial monitoring is not required. It can also be used by the installation and service company or by the commissioning authority to troubleshoot and program from remote locations. One-way dial can also be used to dial into remote site LANs or sub-networks.

Two modems are required, one located at the remote computer and one at the system site. Typically, the DDC operating software must be installed on the remote computer.

Communication
Communication between two different devices controlling equipment, requires a common protocol, a common communication speed and known data formatting. Vendors build their devices around these criteria, so communication between devices by the same manufacturer is routine.

Third Party Interfaces
In many installations, it is desirable for a proprietary building DDC system to communicate with other proprietary DDC systems controlling pieces of equipment. Examples would include a building DDC system and a chiller DDC system (Figure 19) or a fume hood DDC system. Communication between the two systems will require an interface or gateway, due to different proprietary protocols, communication speeds and data formatting.

The gateway or interface translates protocol between the two proprietary systems. The proper operation of the gateway is dependent on the continued use of the specific revised levels of software on both systems. It typically requires the support of the manufacturer at the corporate level to implement and cooperation between the manufacturers. In addition, the costs can vary widely.

Protocols
In the DDC world, there are the three classifications of protocols: closed protocol, open protocol and standard protocol.

A closed protocol is a proprietary protocol used by a specific equipment manufacturer. An open protocol system uses a protocol available to anyone, but not published by a standards organization. A standard protocol system uses a protocol available to anyone. It is created by a standards organization.

Open Systems

An open system is defined as a system that allows components from different manufacturers to co-exist on the same network. These components would not need a gateway to communicate with one another and would not require a manufacturer specific workstation to visualize data. This would allow more than one vendor’s product to meet a specific application requirement.

The sole use of an open or standard protocol does not guarantee that a DDC system will be an open system. A manufacturer has the ability to use open or standard protocols, yet create a closed system, thus continuing a building owner’s dependence on a single manufacturer. This can be accomplished by using unique communication speeds, unique data formatting and by not adopting the full range of an open protocol.

Note: A building owner/engineer should thoroughly research a manufacturer’s claim of an open system.

BACNET
BACNET is a standard protocol published by a standards organization (American Society of Heating, Refrigerating and Air-conditioning Engineers or ASHRAE). It is a specification for a protocol. DDC vendors create a communication protocol that complies with this specification.

BACNET is a relatively complex standard. The standard defines protocol implementation conformance statements (PICS) that define different levels of compliance. A given vendor may or may not support the level required for a given application. In other words, a vendor could meet a very low level of compliance and be BACNET-compatible. The key question is, “At what level?”

In Figure 20 the chiller control unit’s DDC will communicate with the building DDC system if each has a BACNET gateway and their PICS match.

Native BACNET
If a vendor states their product is native BACNET, they are using the BACNET protocol in lieu of a proprietary protocol on their LAN. In Figure 20, a native BACNET building system would be able to communicate to the chiller control DDC with one less gateway.

Overlay Systems

An overlay system is a high-end workstation that communicates with multiple manufacturers’ proprietary EMS systems. An overlay system supplier creates drivers to “talk” to the different systems. The vendors must have a cooperative relationship and revision control is important for continued successful use. The workstation typically displays data, allows manual control and setpoint changes, and handles alarms and messaging. Any detailed editing of the control sequence will still require knowledge of the underlying proprietary software.

LON
The Echelon Corporation has created an open protocol that uses a standard processor and a set of standard transceivers, which allows components from different manufacturers to co-exist on the same LAN. The protocol is available to anyone and is called LONTALK. A unique chip is required for any device that uses LON. Standard network variable formats have been established to allow the transfer of data from one device to another regardless of origin.

Presently, various vendors are competing to become the defacto standard for the network database structure. The network database is a map of the components and the relationship of the data moving between them. The operator workstation needs this structure to visualize the data.

Software suppliers providing the software for the operator workstation may be independent of those providing the software for the database structure and the EMS vendors. 

Elements of a DDC System <3>

Controller Classification
Controllers can be categorized by their capabilities and their methods of communicating (controller-to-controller). In general, there are two classifications of controller - primary control units and secondary control units

Primary controllers typically have the following features:
 

Real-time accurate clock function

Full software compliment

Larger total point capacity

Support for global strategies

Buffer for alarms/messages/trend & runtime data

Freeform programming

Downloadable database

Higher analog/digital converter resolution

Built-in communication interface for PC connection.

Secondary controllers typically have the following features:

Not necessarily 100% standalone

Limited software compliment

Smaller total point count

Freeform or application specific software

Typically lower analog-to-digital converter resolution

Trend data not typically stored at this level

Typical application is terminal equipment or small central station equipment.

Operator Interfaces
The next critical element in the system architecture is an operator interface. Operator interfaces are required to:

See data

Program the system

Exercise manual control

Store long term data

Provide a dynamic graphical interface.

There are five basic types of operator interfaces. They include:

Desktop computers which act as operator workstations

Notebook computers which act as portable operator workstations

Keypad type liquid crystal displays

Handheld consoles/ palmtops/ service tools

Smart thermostats

Desktop computers are centralized operator workstations where the main function is programming, building and visualizing system graphics; long term data collection; and alarm and message filtering.

Notebook computers may connect to the LAN through a communication interface that stands alone or is built into another device. The notebook computer connected to the LAN at a particular level may not have the same capability as a computer connected to the LAN at a higher level.

Keypad liquid crystal displays typically are limited to point monitoring and control. They may have some limited programming capability, such as changing a set point or time schedule.

Handheld consoles, palmtops and service tools are proprietary devices that connect to primary controllers or secondary controllers. Typically they allow point monitoring and control, controller configurations (addressing and communication set-up), and calibration of inputs and outputs.

Smart thermostats are sensors with additional capabilities. They connect to secondary controllers and have a service mode to allow for point monitoring, control and calibration. They also have a user mode that allows point information to be displayed, setpoint adjustment and an override mode.

PC/Network Interface
The communications interface shown in the Figure 11 is a communication interface device. It provides the path between devices that do not use the same communications protocol. This includes computers, modems and printers.

It may be a stand-alone component or it may be built into another device as shown in Figure 12. 

 

Each communications interface on Figure 12 may:

Translate protocol

Provide a communication buffer

Provide temporary memory storage for information being passed between the network and the external PC, modem or printer (mailbox function)

Larger System Architectures
When systems become larger than the capacity of a single sub-network, a higher level of architecture is added to allow the use of multiple sub-networks.

The site LAN wide area network or WAN is used to connect multiple sub-networks and site computers. Multiple sub-networks can be connected to a single site LAN/WAN that allows information sharing between devices on different sub-networks (Figure 13). There may be a limitation on the number of site computers. The site LAN/WAN may include routers if TCP/IP is used. If no routers are used, the protocol can be totally proprietary. If TCP/IP is used, the EMS site LAN/WAN can be the information system backbone within the facility or between facilities.

Multiple site computers can be added to the site LAN/WAN. They can connect the site LAN/WAN via a communications interface, which may be a router. Site LAN/WAN computers can send and receive information from the entire system. Information can be received by each of the site computers, but can not be subsequently shared from one computer to another. Sub-network computers may only be able to see their own sub-network.

Site LANs allow multiple computers to communicate with each other. They may use commercially available computer network software and hardware. Messages, alarms and other data can be re-routed to other computers on the primary site LAN. Information stored in other computers can be remotely accessed. This includes graphics, programming and stored trend and operational data.

Combined Components

  Some vendors combine multiple functions into a single device. In the following system architecture, Figure 14, the communication interface is built into the primary controller. A peer-to-peer LAN or sub-network is connected directly to the device.

In Figure 15, the key component in the system consists of a communication interface, a primary controller and an interface to the secondary polling network.

The addition of a site LAN allows a system to gain size in terms of the number of devices that are served, but in some applications, the location of the devices, rather than the number of devices, is the bigger challenge. In this situation, modem-based communication is used to expand the geography of the system.

Auto-Answer/Auto-Dial System Architecture
In auto-answer/auto dial systems, a specialized communication interface is substituted which introduces a modem and phone lines into the standard architecture. These communication interfaces are made with built-in modems or use external commercial modems. Auto-answer/auto-dial configurations are used to provide monitoring and access to remote buildings. They are used where traditional direct-wiring methods are impractical; and where central site monitoring is desired; or where remote access to controllers is desired.

In an auto-answer/auto-dial system, the central communications interface may call the individual sites or vice versa. Information and data can be passed to and from the layer above the central communications interface (Figure 16).

The auto-answer/auto-dial LAN architecture is typically used by installations with multiple facilities where control and monitoring needs to be centralized. Multiple LANs are used to maintain the groupings of devices, or to separate controllers into defined groups. 

Elements of a DDC System <2>

Controller

A control loop requires a sensor to measure the process variable, control logic to process data, as well as calculate an instruction, and a controlled device to execute the instruction. A controller is defined as a device that has inputs (sensors), outputs (controllable devices) and the ability to execute control logic (software) (Figure 7).



LAN Communication

Communications between devices on a network can be characterized as peer-to-peer or polling. On a peer-to-peer LAN, each device can share information with any other device on the LAN without going through a communications manager (Figure 8).

 

 

The controllers on the peer-to-peer LAN may be primary controllers, secondary controllers or they may be a mix of both types of controllers. The type of controllers that use the peer-to-peer LAN vary between manufacturers. These controller types are defined later in this section.

In a polling controller LAN, the individual controllers can not pass information directly to each other. Instead, data flows from one controller to the interface and then from the interface to the other controller (Figure 9).

The interface device manages communication between the polling LAN controllers and the higher levels in the system architecture. It may also supplement the capability of polling LAN controllers by providing the following functions: clock functions; buffer for trend data, alarms, messages; and higher order software support.

Many systems combine the communications of a peer-to-peer network with a polling network. In Figure 10, the interface communicates in a peer-to-peer fashion with the devices on the peer-to-peer LAN. The polling LAN-based devices can receive data from the peer-to-peer devices, but the data must flow through the interface.

Elements of a Direct Digital Control System

Handbook for DDC and application 

   
Points
The word points is used to describe data storage locations within a DDC system. Data can come from sensors or from software calculations and logic. Data can also be sent to controlled devices or software calculations and logic. Each data storage location has a unique means of identification or addressing.

Direct digital controls (DDC) data can be classified three different ways - by data type, data flow and data source.

Data Type
Data type is classified as digital, analog or accumulating. Digital data may also be called discrete data or binary data. The value of the data is either 0 or 1 and usually represents the state or status of a set of contacts. Analog data are numeric, decimal numbers and typically have varying electrical inputs that are a function of temperature, relative humidity, pressure or some other common HVAC sensed variable. Accumulating data are also numeric, decimal numbers, where the resulting sum is stored. This type of data is sometimes called pulse input.

Data Flow
Data flow refers to whether the data are going into or out of the DDC component/logic. Input points describe data used as input information and output points describe data that are output information.

Data Source
Points can be classified as external points if the data are received from an external device or sent to an external device. External points are sometimes referred to as hardware points. External points may be digital, analog or accumulating and they may be input or output points. Internal points represent data that are created by the logic of the control software. These points may be digital, analog or accumulating. Other terms used to describe these points are virtual points, numeric points, data points and software points.

Global or in-direct points are terms used to describe data that are transmitted on the network for use by other controllers. These points may also be digital, analog or accumulating.

Analog input points typically imply an external point and represent a value that varies over time. Typical analog inputs for HVAC applications are temperature, pressure, relative humidity, carbon dioxide and airflow measurements. Typical analog outputs include control signals for modulating valve positions, damper positions and variable frequency drive speed.

Typical digital inputs for HVAC applications represent the status (example: whether or not the motor is running) of fans, pumps, motors, lighting contactors, etc. A temperature high limit is considered a digital input because, although it is monitoring an analog value (temperature), the information that is transmitted to the controller is a digital condition (whether or not the temperature has exceeded a defined value). Digital outputs are typically motors or other devices that are commanded “on” or “off.” Digital outputs include fans, pumps, two-position (solenoid) valves, lighting contactors, etc.

A “true” analog output (voltage or current) is a varying DC voltage or milliamp signal that is used to drive a transducer or controlled device. Another type of analog output is pulse width modulation (PWM). PWM is accomplished by monitoring a timed closure of a set of contacts. The amount of time the contacts are closed is proportional to a level of performance for the controlled device.

Software Characteristics
There are basically three common approaches used to program the logic of DDC systems. They are line programming, template or menu-based programming and graphical or block programming.

Line programming-based systems use Basic or FORTRAN-like languages with HVAC subroutines. A familiarity with computer programming is helpful in understanding and writing logic for HVAC applications.

Menu-driven, database or template/tabular programming involves the use of templates for common HVAC logical functions. These templates contain the detailed parameters necessary for the functioning of each logical program block. Data flow (how one block is connected to another or where its data comes from) is programmed in each template.

Graphical or block programming is an extension of tabular programming in that graphical representations of the individual function blocks are depicted using graphical symbols connected by data flow lines. The process is depicted with symbols as on electrical schematics and pneumatic control diagrams. Graphical diagrams are created and the detailed data are entered in background menus or screens.

Architecture
System architecture is the term used to describe the overall local area network or LAN structure, where the operator interfaces connect to the system and how one may remotely communicate to the system. It is the map or layout of the system.

The network or LAN is the medium that connects multiple intelligent devices. It allows these devices to communicate, share information, display and print information, as well as store data. The most basic task of the system architecture is to connect the DDC controllers so that information can be shared between them.
 

Introduction to Direct Digital Control Systems (2)

Basic Control Loop
The control loop shown in Figure 1 consists of three main components: a sensor, a controller and a controlled device. These three components or functions interact to control a medium. In the example shown in Figure 1, air temperature is the controlled medium. The sensor measures the data, the controller processes the data and the controlled device causes an action.

The Figure 1 could be an example of a pneumatic or electronic control system, where the controller is a separate and distinct piece of hardware. In a DDC system, the controller “function” takes place in software as shown in Figure 2.

Sensor
The sensor measures the controlled medium or other control input in an accurate and repeatable manner. Common HVAC sensors are used to measure temperature, pressure, relative humidity, airflow stateand carbon dioxide. Other variables may also be measured that impact the controller logic. Examples include other temperatures, time-of-day or the current demand condition. Additional input information (sensed data) that influences the control logic may include the status of other parameters (airflow, water flow, current) or safety (fire, smoke, high/low temperature limit or any number of other physical parameters). Sensors are an extremely important part of the control system and can be the first, as well as a major, weak link in the chain of control.

Controller
The controller processes data that is input from the sensor, applies the logic of control and causes an output action to be generated. This signal may be sent directly to the controlled device or to other logical control functions and ultimately to the controlled device. The controller’s function is to compare it’s input (from the sensor) with a set of instructions such as setpoint, throttling range and action, then produce an appropriate output signal. This is the logic of control. It usually consists of a control response along with other logical decisions that are unique to the specific control application. How the controller functions is referred to as the control response. Control responses are typically one the following:

Two-Position
Floating
Proportional (P only)
Proportional plus Integral (PI)
Proportional plus Integral plus Derivative (PID)

Controlled Device or Output
A controlled device is a device that responds to the signal from the controller, or the control logic, and changes the condition of the controlled medium or the state of the end device. These devices include valve operators, damper operators, electric relays, fans, pumps, compressors and variable speed drives for fan and pump applications.
 

Introduction to Direct Digital Control Systems

Purpose of this Guide
The purpose of this guide is to describe, in generic terms, the various architectures, hardware components and software associated with Direct Digital Control (DDC) systems. To accomplish this goal, a generic framework of the various components and configurations used in current DDC systems has been defined. This framework is used as a yardstick for several DDC manufacturers so readers may compare the relative features and benefits.

Intended Audience

Due to the complexity and proprietary nature of DDC systems, it has become difficult to stay current with the designs, installations, operation and maintenance of DDC systems. This guide was developed specifically to help building owners and consulting/specifying engineers with these issues.

What is an Energy Management System?
For the purposes of this guide, an energy management system (EMS) is defined as a fully functional control system. This includes controllers, various communications devices and the full complement of operational software necessary to have a fully functioning control system. This guide addresses approximately twenty of the DDC vendors who serve the institutional and commercial marketplace in the United States. Vendors who supply a complete line of all the necessary hardware and software are included. This guide does not cover specialty markets (retail grocery, hotels), nor does it cover industrial or process controls.

What is Control?
The process of controlling an HVAC system involves three steps. These steps include first measuring data, then processing the data with other information and finally causing a control action. These three functions make up what is known as a control loop. An example of this process is depicted in Figure 1.

 

(OOT) Pilih kertas atau emas jilid3

*Masa Uang Gunting Sjafruddin*

Masa uang rupiah ?gunting Sjarifuddin- dimulai pada bulan Maret 1950 sampai dihapuskannya dan digantikannya dengan uang rupiah Orba tahun 1959. Yang dimaksud dengan gunting Sjarifuddin ialah keputusan pemerintah untuk menggunting pecahan mata uang rupiah di atas Rp 5 menjadi dua. Potongan bagian kanan tidak berlaku dan potongan sebalah kiri berlaku dengan nilai hanya setengahnya. Dan rupiah pun didevaluasi dari Rp 11,40 per US$ menjadi Rp 45 per US$. Artinya harga emas naik dari Rp 13 per gram menjadi Rp 51 per gram. Pada waktu itu keadaan jadi heboh. Pengumuman sanering (pengguntingan uang) ini dilakukan melalui radio dan pada saat itu tidak banyak yang memiliki radio. Sehingga mereka yang tahu kemudian berbondong-bondong memborong barang. Yang kasihan adalah para pedagang, karena barang dagangannya habis, tetapi ketika mereka hendak melakukan kulakan uang yang diperolehnya sudah turun harganya. Modalnya susut banyak. Tetapi, bukan hanya pedagang yang rugi, tetapi semua orang yang memiliki uang. Nilai uang susut paling tidak 50% dalam sekejap saja.

Antara tahun 1950 sampai tahun 1959, walaupun Bank Indonesia melakukan pembantaian terhadap para pedagang, penabung, pemilik uang di tahun 1950, tetapi kalau saya lihat, Indonesia masih tergolong makmur, dibanding dengan kondisi sekarang, jaman reformasi. Indikator saya ialah banyaknya mahasiswa yang berani berkeluarga dan punya anak pada saat mereka masih kuliah. Pada jaman reformasi ini, untuk berkeluarga, seorang mahasiswa harus lulus dan bekerja beberapa tahun dulu. Artinya, dulu lebih makmur dari sekarang dan indikasinya adalah banyak mahasiswa bisa bekerja dan memperoleh penghasilan yang bisa menghidupi keluarga.

*Masa ORI dan Perang Kemerdekaan - Merdeka Mencetak Uang Semaunya*

Masa yang paling kacau adalah mulai dari pendudukan Jepang sampai masa perang kemerdekaan. Terlalu banyak otoritas keuangan (baca: Bank Sentral). Bermacam-macam uang dikeluarkan selama periode ini. Dari uang pendudukan Jepang yang dikeluarkan beberapa bank, uang NICA (pendudukan Belanda), uang daerah Sumatra Utara, Banten, Jambi, dan deret lagi di daerah repupblik. Bahkan di Yogya ada paling tidak dua jenis, yaitu yang dikeluarkan oleh Pakualaman dan oleh Kraton Yogya. Kita bicara saja uang republik yang paling resmi yaitu ORI - Oeang Republik Indonesia, walaupun sebenarnya uang-uang lainnya berlaku (kecuali uang pendudukan Jepang yang ditarik pada tahun 1946). Ketika ORI dikeluarkan dengan dektrit no 19 tahun 1946 pada tanggal 25 Oktober 1946 mempunyai nilai tukar terhadap uang sejati (emas) Rp 2 = 1 gram emas. Jadi Rp 1 ORI pada saat dikeluarkan punya nilai dan daya beli setara dengan Rp 100.000 uang sekarang (tahun 2007).

Pada saat dikeluarkannya, mungkin bank sentral republik waktu itu masih naif, (mungkin juga tidak) mereka membagikan Rp 1 kepada setiap warga negara, anak-anak, pemuda, orang tua, semua dapat bagian. Mertua saya menceritakan betapa senang dia mendapat uang itu bagai mendapat durian runtuh. Dia pakai untuk jajan. Awalnya uang Rp 1 ORI bisa dipakai untuk beli nasi dan lauk pauknya beberapa porsi. Setelah beberapa hari pedagang menaikkan harga-harga. Tindakan para pedagang bisa dimaklumi karena uang tidak enak dan tidak mengenyangkan, lain halnya dengan makanan atau pakaian yang mempunyai manfaat yang nyata.

Saya katakan jaman itu sebagai jaman kebebasan mencetak uang, contohnya ialah, pada tahun 1946 pecahan terbesar adalah Rp 100. Tahun 1947 pecahan terbesar naik menjadi Rp 250, kemudian dicetak lagi Rp 400 pada tahun 1948. Tidak hanya itu, banyak daerah seperti Sumatra Utara, Jambi,Banten, Palembang, Aceh, Lampung dan entah mana lagi juga mengeluarkan uangnya sendiri. Bahkan, kata mertua saya, di Jogya, ada dua uang daerah, yaitu yang dikeluarkan oleh Pakualaman dan yang dikeluarkan Keraton Jogya. Tidak heran kalau harga-harga tidak terkendali. Sebagai patokan, pada saat ORI dikeluarkan, nilai tukarnya terhadap uang sejati (emas) 1gr emas = Rp 2 dan setelah gunting Sjafruddin diberlakukan 1 gr emas = Rp 51 hanya dalam kurun waktu 4 tahun.

*Masa Jaman Nornal*

Nama resminya yang diberikan oleh para penulis buku sejarah adalah jaman penjajahan Belanda. Sedangkan oleh kakek nenek yang berumur di atas 80 tahun, jaman itu disebut jaman normal, terutama pada periode sebelum tahun 1930an. Bisa dimengerti bahwa para penulis buku sejarah yang direstui oleh pemerintah memberi nama yang berkonotasi negatif, karena untuk mendiskreditkan pemerintahan yang lalu (Belanda). Dan Belanda yang tidak ikut menyusun buku sejarah Indonesia, tidak bisa membela diri.

Seperti halnya dengan kata Orde Lama, bernada negatif karena nama itu adalah pemberian pemerintahan berikutnya (Orba) dan pada saat penulisan sejarah itu politikus Orla sudah disingkirkan habis-habisan pada saat pergantian rejim. Berbeda halnya dengan jaman Reformasi, walaupun ada pergantian rejim, nama Orba masih dipakai karena masih banyak anasir-anasir Orba yang bercokol di dalam Orde Reformasi. Jadi sulit nama Orba ditukar menjadi Orde Lepas Landas Nyungsep, atau nama yang konotasi negatif lainnya.

Jaman penjajahan Belanda walaupun nama resminya berkonotasi negatif, kakek nenek kita menyebutnya dengan nama yang megah yaitu Jaman Normal. Seakan-akan Jaman Revolusi, Jaman Sukarno atau Jaman Orba, tidak bias dikategorikan sebagai jaman yang normal. Memang demikian. Ciri Jaman

Normal menurut mereka ialah harga barang tidak beranjak kemana-mana alias tetap. Hanya bapak yang kerja dan bisa menghidupi anak sampai 12 dan istri. Cukup sandang dan pangan. Gaji 1 bulan bisa dipakai foya-foya 40 hari (artinya tanpa harus menghemat, mereka masih bisa menabung). Dibandingkan dengan kondisi sekarang, ibu dan bapak bekerja untuk membiayai rumah dengan anak 2 orang dan masih mengeluhkan gaji yang pas-pasan.

Merasa masih penasaran dengan tingkat kemakmuran masa itu, saya tanyakan kepada mertua, berapa harga rumah dan makan dengan lauk yang wajar.

Harga rumah di Kali Urang 1000 Gulden. Makan nasi dengan lauk, sayur dan minum 0,5 sen. Dengan kata lain harga rumah dulu adalah setara dengan 200.000 porsi nasi rames. Kalau sekarang harga nasi rames Rp 10.000 dan dianggap bahwa harga rumah yang bagus di Kali Urang setara dengan 200.000 porsi nasi rames, maka harga sekarang adalah Rp 2 milyar. Kira-kira itulah harga rumah yang bagus di daerah itu. Jadi kalau rata-rata 1 keluarga terdiri dari 2 orang tua dan 10 orang anak dan bias makan foya-foya selama 40 hari, pasti penghasilannya setara dengan 4,8juta sampai 14,4 juta lebih, karena faktor foya-foya harusdiperhitungkan. Ayah dari mertua saya adalah guru bantu. Gajinya 50 gulden per bulan atau setara dengan 10.000 porsi nasi rames. Jumlah ini mempunyai daya beli setara dengan Rp 100 juta per bulan uang 2007 (nasi rames Rp 10.000 per porsi). Dengan penghasilan seperti itu, istri tidak perlu kerja.

Gaji pembantu waktu itu 75 sen per bulan atau setara dengan 150 porsi nasi rames. Berarti berdaya beli setara dengan Rp 1,5 juta uang saat ini.

Kita bisa telusuri terus gaji-gaji berbagai profesi pada masa itu.

Kesimpulannya bahwa daya beli waktu itu tinggi. Jadi tidak heran kalau jaman penjajahan dulu disebut jaman normal (artinya jaman lainnya tidak normal).

*Catatan Akhir dan Renungan*

Kalau ditanyakan mengenai kemakmuran kepada pelaku ekonomi, selama 80 tahun terakhir, yang disebut Indonesia atau dulunya Hindia Belanda, tidak semakin makmur bahkan sebaliknya. Pertumbuhan ekonomi yang spektakuler yang dilaporkan data-data statistik mengikuti kaidah Mark Twain: There are lies, damn lies and statistics. Kalau anda merasa heran, kenapa orang percaya pada janji para politikus, kata Adolf Hitler: ?Make the lie big, make it simple, keep saying it, and eventually they will believe it- (Buatlah kebohongan besar dan susunlah sesederhana mungkin, dengungkan terus dan akhirnya orang akan percaya).

Setiap jaman di republik ini punya tema kebohongan. “Merdeka- dan “revolusi- jaman Sukarno, “Pembangunan-, “Lepas Landas- di jaman Suharto, dan “Demokrasi, Otonomi Daerah, Reformasi- jaman sekarang. Kalau janji demi janji didengungkan terus menerus seperti yang dilakukan Hitler dan mentri propagandanya Joseph Goebbels, orang akan percaya, kecuali orang yang berpikir dan menganalisa.

Kemakmuran tidak bisa diciptakan dengan membuat undang-undang atau aktifitas-aktifitas berpolitik. Apakah padi akan tumbuh lebih subur atau minyak sawit keluar lebih banyak karena para politikus dan birokrat bersidang lebih lama atau undang-undang bertambah banyak? Atau orang lebih banyak ikut partai politik, organisasi kedaerahan? Untuk orang berpikirnya sederhana seperti saya ini, padi hanya akan tumbuh subur, kebun hanya akan berbuah lebih banyak, pabrik hanya bisa menghasilkan sepatu yang lebih banyak dan baik kalau orang bekerja di sawah, kebun atau pabrik lebih effisien dan lebih giat. Jadi kalau selama 6 dekade trendnya bukan terfokus pada aktifitas langsung untuk menaikkan kemakmuran, maka jangan mengharapkan hasil yang berbeda. Hanya orang gila atau idiot yang mengharapkan hasil yang berbeda sementara apa yang dikerjakan dan cara mengerjakannya sama. Itulah sebabnya saya skeptic  bahwa GDP US$ 18.000 per tahun identik dengan kemakmuran. Saya tidak yakin kemakmuran akan dicapai dalam 2-5 dekade ke depan.

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