MODBUS comparison

Since the MODBUS is well known, it is easy to get the general idea by listing the main differences between the protocols:

• The IOCOM is event based, while MODBUS uses polling. This means that data is transferred when it changes, not when it is queried.
• Data transfers are synchronized in way that it guarantees that other end of communication receives changes in same order the changes are made.
• IOCOM uses compression, flow control, etc and aims for performance. This makes it more complex than MODBUS. While most MODBUS users write their own protocol implementation, I do not expect this to work well with IOCOM. I recommend using reference implementation, at least as starting point, unless there is need to port the protocol to Python, Java, etc.
• IOCOM requires full duplex serial communication (at least logically), half duplex will not do. It cannot do “one master – multiple slaves” serial communication, every device needs it’s own serial wire. If those features are important, then use MODBUS. It was designed specifically for that scenario and does it well.
• IOCOM handles secure TLS connections natively.

190901, updated 22.5.2020/pekka