Comparison between IEC60870-5-103 and MODBUS RTU


Thread Starter

Vikram Dandekar

I need to submit a comparison between these protocols to a Utility customer planning to integrate all his protection and metering devices onto DMS on IEC 60870-5-104.

We are trying to convince the customer to go for MODBUS RTU devices but we need convincing arguments.
In the title you mention 103, which is a serial protocol, and in the body you mention 104, which is a TCP/IP-based protocol. Either way, both 103 and 104 are considerably different than Modbus RTU and Modbus TPC, which I'm sure you know.

If all your customer wants to do is send/receive values to/from a device, then Modbus RTU will do fine. If your customer wants to send/receive values with time stamps, and use other commands, which aren’t inherent to the Modbus protocol, then 103/104 may be the way to go.

When choosing devices to communicate with, your selections will be somewhat limited when using the 103/104 protocol, compared to Modbus (which just about every I/O manufacturer supports).

I like easy.. Modbus is easy, where 103/104 has a fairly sharp learning curve.


Charlie Gill

Although my background is not in power utilities, I am now in the process of adding a SCADA system to a power house with 4 turbine generators and associated switch gear. I have found that ALL the equipment that I need to interface to (governor, exciter, machine protection, power meter, and breaker protection) supports Modbus RTU. There was no other common protocol supported.

I was impressed.

Charlie Gill
When you are working on a DMS, you are talking of the Wide Area systems. For that reason I am strongly recomend IEC- 103, IEC -101, or better IEC- 104, DNP 3.0 over TCP/IP. The last protocols only sends the last changes, that means less bandwith than Modbus. Also for electrical system is got to know the time stamping that is not supported by Modbus.

Sorry for that, my comentaries will not help you.
I have a mini SCADA at my workplace using 3 D20 RTU and Modbus Protocol, but i have a problem where one or more modul in RTU is invalid. We use PLC(Power Line Communication) with speed 300 baud and 1200 baud. 3 RTU connect in radial (RTU C to RTU B with 300 baud, RTU B to RTU A with 1200 baud, and RTU A to Master Station with 1200 baud).

For the email below, i think my problem is caused by low bandwith of my PLC communication. So i want to ask somebody who knows detail about this and the solution. Should i change my SCADA protocol with others which more powerfull in PLC communication.