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Modbus Checklist
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Modbus Checklist

Owned by Giuseppe Pagano (Deactivated)
Last updated: 02.Aug 2023
1 min read

The terminology changed according to modbus.org. Unfortunately, this conversion has not yet been completed here.

Update to the newest stable Revolution Pi Image

Update PiCtory to the newest version.

Modbus RTU

Set the timing of the action interval to 1000ms. This is the default value.
Check if the Extended Data in the Modbus RTU Master is set correctly.
Do the addresses and the access function fit to the slave?
Are there any empty data?

Modbus TCP

  • So far, there is no need for action here.

Client application

Check the status of the background daemons
sudo service pimodbus-master.service

Output

Fix

Output

Fix

Unit pimodbus-master.service.service could not be found.
sudo revpi-config enable pimodbus-master Created symlink /etc/systemd/system/multi-user.target.wants/pimodbus-master.service → /lib/systemd/system/pimodbus-master.service. 0

Server application

Check the status of the background daemons
sudo service pimodbus-slave.service

Output

Fix

Output

Fix

Unit pimodbus-slave.service.service could not be found.
sudo revpi-config enable pimodbus-slave Created symlink

Troubleshooting

Check if the Modbus Service is Running correctly by inspecting the log to see if the Modbus demon outputs errors
tail -f /var/log/daemon.log # type CTRL+C to exit from here
Check error codes according to the documentation RevPi as Modbus RTU Master | Industrial Raspberry Pi
piTest -1 -r Modbus_Master_Status piTest -1 -r Modbus_Action_Status_1

Output

Fix

Output

Fix

Cannot find variable 'Modbus_Master_Status'

Check the PiCtory configuration

RevPi as Modbus RTU Master | Industrial Raspberry Pi

1 Byte-Value of Modbus_Action_Status_1: 255 dez (=ff hex)

Check the “Extended Data” configuration

RevPi as Modbus RTU Master | Industrial Raspberry Pi

 

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