We have Modbus Master communicating to 10 Modbus slaves over RS485 2 wire bus. (All the slaves connected to bus in multi-drop)
If the setup is using ASCII standard, the communication is stable and working fine.
When we use Binary standard, It is not working properly. When I analyzed the issue, I came to know that the received packets are getting corrupted in the slave.
When any slave is sending response to the corresponding master request, that response is in turn going to all other 9 slaves as a new request again.
This is happening since they are connected in multi drop 2 wire mode. In that case the other slaves are not able to reject it before a new real request
comes from master.
In ASCII mode it is working because there is a proper start) and stop(\r) characters to identify the packet even if there is a overflow of requests.
where as in Binary mode the start and stop are identified by the time delay. If the requests are overflown then slave is not able to recognize the start and stop of the message.
Is Multi-drop configuration is allowed for the 2 wire RS485 ?
If yes suggest me how to handle the above issue?
If the setup is using ASCII standard, the communication is stable and working fine.
When we use Binary standard, It is not working properly. When I analyzed the issue, I came to know that the received packets are getting corrupted in the slave.
When any slave is sending response to the corresponding master request, that response is in turn going to all other 9 slaves as a new request again.
This is happening since they are connected in multi drop 2 wire mode. In that case the other slaves are not able to reject it before a new real request
comes from master.
In ASCII mode it is working because there is a proper start) and stop(\r) characters to identify the packet even if there is a overflow of requests.
where as in Binary mode the start and stop are identified by the time delay. If the requests are overflown then slave is not able to recognize the start and stop of the message.
Is Multi-drop configuration is allowed for the 2 wire RS485 ?
If yes suggest me how to handle the above issue?