modbus and iec 870-5-102

IEC870-5-102 is a communication protocol used for (energy) meter reading and similar.

Modbus is another communication protocol used in automation business. It was originally used by Allen Bradley but is today commonly used. There is ascii and binary ("RTU") when it comes to serial and "Modbus/TCP" when it comes to ethernet.

These protocols don't have much in common.

"yeti" skrev i meddelandet news: snipped-for-privacy@i40g2000cwc.googlegroups.com...

Minor nit-pick: Modbus was developed and widely used by *Modicon*, not Allen-Bradley.

A-B never have, and likely never will, push Modbus. They consider their DF1 core protocol far superior (it's multi-master for a start).

Cameron:-)

To nit-pick a nit-pick, AIUI, Modbus was originated at Gould Electronics, subsequently taken over by AEG Modicon Inc and now Schneider Electric/Telemechanique.

It is a simple, open, protocol, unlike Allen-Bradley's DF1 which has a more complicated handshaking for each transaction, and now has some closed, undocumented features. However, like all standards, Modbus got subjected to different interpretations and extensions (e.g. whether to number registers from 0 or 1, and which byte order to send floating-point numbers in), and different manufacturers' implementations are not always compatible.

Chris

To nit-pick a nit-pick on a nit-pick ...