jvan (Customer) asked a question.
Modbus and 2-Wire Control
I have a pump application where a GS20 is controlling a constant pressure pump. There are several things I'm looking to achieve:
- A drive that can reliably control itself, with no user intervention. This means it will automatically resume operation after a power outage, and attempt to restart after an alarm.
- A method to stop the drive via RS-485 Modbus, should the system encounter a problem.
The first point is more or less checked. It seems the most reliable way to accomplish that is using 2-Wire control and enabling P02.35.
I'm now hung up on how to stop the drive via Modbus in the situation above. Are there any better options or scenarios I should explore here?
We are assuming you are not controlling the stop/start of the drive with RS-485 since you mentioned 2-wire control.
In this case, you can use RS-485 to set the external fault or base block bit and this will stop the drive. Modbus write to register 2002 ( 48195-modbus decimal) , bit 0 . External fault. Or Bit 2 base block on. Both will stop the drive in different ways depending on the application needs.
Thanks for the info. The Base Block functionality will work perfect! This is just an override in the situation of an external fault. Otherwise, the drive needs to be enabled at all times.