To determine the difference between RTU and PLC with the current implemented technology somehow become very difficult due to the used technology on both of the terms as well as the available features already become similar.
Initially, the RTU is refer to a controller (more common as Single Board panel mounted) that be placed remotely (therefore it is absolutely facilitate with serial communication feature), and just perform data acquisition (conversion of electrical signal to digital data) without any high-level programming capability.
While PLC (modular / rack-mounted), is more dedicated to a process control to perform standalone automatic control (therefore it is absolutely facilitate with highlevel programming capability, such as Ladder Logic and/or Sequential Text Command), and the communication capability is just optional.
Currently both of the RTU and PLC has communication port(s), support multi-protocols Modbus, DNP, IEC 60870-5, etc), has 'programmable' capability (IEC 61131-3), and Modular.
By now, most of the major brand PLCs (AB, Siemens, Modicon, GE Fanuc, etc.) support for multi-protocols, either it through their native communication module/port and/or through a third party communication module provider (such as ProSoft for AB PLC).
Therefore, personally, I would just call both of it as 'Controller' and determine it as : 1. General Purpose Controller 2. Specific Application Controller - IED, in electrical area, such as Bay Controller, Power Monitor, Protection Relay, etc. - in oil & gas area, such as Batch Controller, Flow Computer/Controller, Pump Controller, etc. 3. Integrated Controller/Sensor
- Fieldbus Instrument, Smart Fire & Gas Detector, etc.
Communication Interface
In general, any Controller with communication port shall be able to be connected to any data telecommunication infrastructure, either it direct wire, fiber optic, microwave, power line carrier, dedicated/leased line, etc. Telecommunication infrastructure shall be transparent to the data, therefore we just need to assure that the physical interface between the PLC and Data Telecommunication infrastructure is same, and you will get the data in the other site is similar as what you sent.
Initially, the RTU is refer to a controller (more common as Single Board panel mounted) that be placed remotely (therefore it is absolutely facilitate with serial communication feature), and just perform data acquisition (conversion of electrical signal to digital data) without any high-level programming capability.
While PLC (modular / rack-mounted), is more dedicated to a process control to perform standalone automatic control (therefore it is absolutely facilitate with highlevel programming capability, such as Ladder Logic and/or Sequential Text Command), and the communication capability is just optional.
Currently both of the RTU and PLC has communication port(s), support multi-protocols Modbus, DNP, IEC 60870-5, etc), has 'programmable' capability (IEC 61131-3), and Modular.
By now, most of the major brand PLCs (AB, Siemens, Modicon, GE Fanuc, etc.) support for multi-protocols, either it through their native communication module/port and/or through a third party communication module provider (such as ProSoft for AB PLC).
Therefore, personally, I would just call both of it as 'Controller' and determine it as : 1. General Purpose Controller 2. Specific Application Controller - IED, in electrical area, such as Bay Controller, Power Monitor, Protection Relay, etc. - in oil & gas area, such as Batch Controller, Flow Computer/Controller, Pump Controller, etc. 3. Integrated Controller/Sensor
- Fieldbus Instrument, Smart Fire & Gas Detector, etc.
Communication Interface
In general, any Controller with communication port shall be able to be connected to any data telecommunication infrastructure, either it direct wire, fiber optic, microwave, power line carrier, dedicated/leased line, etc. Telecommunication infrastructure shall be transparent to the data, therefore we just need to assure that the physical interface between the PLC and Data Telecommunication infrastructure is same, and you will get the data in the other site is similar as what you sent.
