Hi All,
I have a RedLion G310 panel which talks to a number of devices via Modbus. The G310 has both RS485 ports installed because one Modbus loop uses a single stop bit and the other two stop bits.
I have a remote PLC that is interrogated on the 'single' stop bit loop. This loop has most of the other devices. The remote PLC is connected via a radio link with an intermediate repeater. Therefore it takes some time for the ModBus packet to reach the remote PLC and sometime for the answer to be returned.
I am apparently getting 'time out' errors when the G310 does not get a returned Modbus frame in time. Or possibly the remote PLC packet is colliding with other traffic because the radios might not be monitoring the loop traffic. What happens is that the G310 sets all the variables requested in the Modbus packet to zero until a valid packet is returned.
I don't need the remote data very frequently and I have set the G310 to poll as slowly as I can.
Question; Is there anyway to tell the G310 NOT to set all variable to zero but to use the old values if a Modbus packet does not arrive in time?
Unfortunately I can't put the remote PLC on the loop with less traffic because it does nto work with two stop bits and there is no other slots available for more RS485 cards.
Ideas would be welcomed. Thanks
I have a RedLion G310 panel which talks to a number of devices via Modbus. The G310 has both RS485 ports installed because one Modbus loop uses a single stop bit and the other two stop bits.
I have a remote PLC that is interrogated on the 'single' stop bit loop. This loop has most of the other devices. The remote PLC is connected via a radio link with an intermediate repeater. Therefore it takes some time for the ModBus packet to reach the remote PLC and sometime for the answer to be returned.
I am apparently getting 'time out' errors when the G310 does not get a returned Modbus frame in time. Or possibly the remote PLC packet is colliding with other traffic because the radios might not be monitoring the loop traffic. What happens is that the G310 sets all the variables requested in the Modbus packet to zero until a valid packet is returned.
I don't need the remote data very frequently and I have set the G310 to poll as slowly as I can.
Question; Is there anyway to tell the G310 NOT to set all variable to zero but to use the old values if a Modbus packet does not arrive in time?
Unfortunately I can't put the remote PLC on the loop with less traffic because it does nto work with two stop bits and there is no other slots available for more RS485 cards.
Ideas would be welcomed. Thanks