Both of those captures simply show the same request packet over and over (no responses). The packet is
01 03 10 00 00 66 20 C1
which is a request to slave address 1 to read 102 holding registers starting at address 0x1000.

Now while a CRC value of 0x20C1 is the correct CRC for the packet, I believe the ordering of the two bytes in the packet are incorrect, as Modbus specifies the CRC shall be encoded low-byte first (the manual you provided for the controller also states exactly that).

So it seems there is a bug in this software and the firmware of the controller where they are both incorrectly encoding the CRC into the packet.

I recommend contacting Mebay regarding this mistake.

 

Both of those captures simply show the same request packet over and over (no responses). The packet is
01 03 10 00 00 66 20 C1
which is a request to slave address 1 to read 102 holding registers starting at address 0x1000.

Now while a CRC value of 0x20C1 is the correct CRC for the packet, I believe the ordering of the two bytes in the packet are incorrect, as Modbus specifies the CRC shall be encoded low-byte first (the manual you provided for the controller also states exactly that).

So it seems there is a bug in this software and the firmware of the controller where they are both incorrectly encoding the CRC into the packet.

I recommend contacting Mebay regarding this mistake.

thank you for your help ,i will contact mebay

 

thank you for your help ,i will contact mebay

the supplier reply
when i change to 0-CRC L_H the software does not dectect the controller

 

If communication was working previously, both the software and the controller must have had their CRC bytes in High to Low order. You need to change this ordering on both the software and the controller, not just the controller.

Changing that setting to Low to High order on the controller should allow it to communicate to other Modbus master software now.

 

If communication was working previously, both the software and the controller must have had their CRC bytes in High to Low order. You need to change this ordering on both the software and the controller, not just the controller.

Changing that setting to Low to High order on the controller should allow it to communicate to other Modbus master software now.

i have changed it to low to High but still not communicate to the modbus

 

Well I don't know what to tell you then. If you have the CRC order at Low to High and all of your communication settings match (baud rate, parity, stop bits, slave address), then communications should work. Maybe you need to power cycle the controller for the settings to take effect.

 

Well I don't know what to tell you then. If you have the CRC order at Low to High and all of your communication settings match (baud rate, parity, stop bits, slave address), then communications should work. Maybe you need to power cycle the controller for the settings to take effect.

i have done that and still not working