debugging ModBus

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alf@emcom.no
Posts: 20
Joined: 25 Sep 2018, 10:17
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debugging ModBus

Post 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
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dirk
KUNBUS
Posts: 1926
Joined: 15 Dec 2016, 13:19
Answers: 4

Re: debugging ModBus

Post 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]
alf@emcom.no
Posts: 20
Joined: 25 Sep 2018, 10:17
Answers: 0

Re: debugging ModBus

Post 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 ?
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dirk
KUNBUS
Posts: 1926
Joined: 15 Dec 2016, 13:19
Answers: 4

Re: debugging ModBus

Post by dirk »

Yes, if you have performed the reset of the Modbus communication accordingly then the values will be updated again.
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