Modbus Poll is a Modbus master simulator designed primarily to help developers of Modbus slave devices or others that want to test and simulate the Modbus protocol. With the multiple document interface you can monitor several Modbus slaves and/or data areas at the same time.
I am trying to poll n schneider Energymeter in having parity as none and stop bit as 2 using a RS485 to USB converter. I am getting connection timed out error. But when I try to poll the same meter with parity as none and stopbit as 1, I am able to receive the data.
The code snippet I am using to poll the meter is as follows
Always I am getting the rc as -1 and the Connection timed out error when converting the errno.
Am I missing anything ?
Mughil ArulMughil Arul
2 Answers
Are you sure that the shop bits should be 2 with no parity? The Modbus specification does state that there should be 11 bits per character for RTU which does mean that there should be 2 stop bits when using no parity. HOWEVER, in my experience, many vendors do not adhere to that rule. I grabbed the first energy meter manual that I could find from the Schneider web site:
On page 47 there is a note 'number of stop bits = 1' that appears to apply to all parity modes.
MarkerMarker
Mughil ArulMughil Arul