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debugging ModBus

Posted: 24 Jan 2019, 11:56
by alf@emcom.no
Hi.
I am using the Modbus master with a physical connection to the RS-485 port on the RevPi Connect.
The Modbus-part is set up, and I read the values with piTest etc.

It seems to work fine, BUT - I saw that if the slave does not answer, the values in the process-image are kept.
How can I pick up on this ?

Alf

Re: debugging ModBus

Posted: 24 Jan 2019, 15:32
by dirk
Hi Alf, you have to read and reset the status values, see here under "Help! Error!"

Modbus_Master_Status
Master_Status_Reset
Modbus_Action_Status_[1… 32]
Action_Status_Reset_[1… 32]

Re: debugging ModBus

Posted: 13 Feb 2019, 17:55
by alf@emcom.no
OK, so I can get the status, but when communication is restored, the read Modbus-values themselves will be updated again, right ?

Re: debugging ModBus

Posted: 14 Feb 2019, 09:33
by dirk
Yes, if you have performed the reset of the Modbus communication accordingly then the values will be updated again.