cdogmillion
Member
Hi all,
Im working on a tank filling project where a pump is started remotely which fills a tank locally.
At the remote location I have a micro820 acting as a remote modbus relay (Slave) to switch on the remote pump.
Its connected via modbus RTU to my local master PLC which is also a micro820.
Master PLC tells the slave PLC to turn the pump on and off, everything is well.
However I have a problem if the following series of events occur:
- Master tells the slave to hold the pump on
- Slave holds the pump contactor on
- There is a connection break in the modbus cable
- Master tells the slave to turn the pump off due to tank being full
- Slave does not receive the message and keeps filling the tank (holds its last value from before the connection broke)
This is a major problem for me if the tanks continue to fill due to a modbus connection break.
So my question is, is there any bit/register/function in connected components workbench which I can use to monitor the status of the modbus link which I can implement to disable the pump output if the slave PLC detects a bad modbus connection?
Cheers
Im working on a tank filling project where a pump is started remotely which fills a tank locally.
At the remote location I have a micro820 acting as a remote modbus relay (Slave) to switch on the remote pump.
Its connected via modbus RTU to my local master PLC which is also a micro820.
Master PLC tells the slave PLC to turn the pump on and off, everything is well.
However I have a problem if the following series of events occur:
- Master tells the slave to hold the pump on
- Slave holds the pump contactor on
- There is a connection break in the modbus cable
- Master tells the slave to turn the pump off due to tank being full
- Slave does not receive the message and keeps filling the tank (holds its last value from before the connection broke)
This is a major problem for me if the tanks continue to fill due to a modbus connection break.
So my question is, is there any bit/register/function in connected components workbench which I can use to monitor the status of the modbus link which I can implement to disable the pump output if the slave PLC detects a bad modbus connection?
Cheers