Modbus TCP/IP issue at configuration

[MathieuD]

Hi, I am working as a newbie on a TM241CE24R to communicate with several IGUS driver dryve D1 with Modbus TCP/IP.

After configurating the generic TCP slave devices on the Ethernet Network and going in run, the drivers are signalling an error without more information.

Do you have any advice or method to follow in order to solve the problem ?

[Bastian_Schmitz]

Did you check the IP address of every driver? It seems the first one is reached (because you could see a MAC adress). In m< opinion you have an ip adress confict. If you start the driver and connect an ethernet cable you should see the configured IP address (explained in the manual). 

Other reasons for the problem could be false configrured Modbus Register adresses. Try to add or sub the address with 1. Some products start with register adress 0 other with 1.

[MathieuD]

Hi Bastian,

At power up, the display is ok : each driver has the correct IP Address from the topology of our environment as attached.

For the MAC address, I wrote it manually to try with BOOTP identification but there was no change. I also modify the Modbus Register addresses, the error is still here.

However, I do not find on Machine Expert where I can define Modbus settings such as port 502, on Machine Expert.

[MathieuD]

Ok, I have some updates from the driver manufacturer.

The driver must receive a frame with Modbus function 43 MEI type 13 (MODBUS Application Protocol 1 1 b page 43 CANopen General Reference Request and Response PDU). So, based on the SEND_RECV_MSG function, I developped a program to send standard frame to the device; the function goes done without error but the received buffer gets unexpected data.

With tool Modbus Poll, when the correct message is forced, the driver responds as expected. While the PLC seems to send message with the first 4 bytes increasing at each sending and there is no similarities with the received buffer.

[MathieuD]

For an unknown reason, the SEND_RECV_MSG function block doesn't work; so I use NBS.TCP_Client, NBS.TCP_Write and NBS.TCP_Read in an assembled function block. It works with one device (able to drive the motor) but not with two.

I moved the NBS.TCP_Client outside of the function block because both instances seemed to have the same Connection but the communication issue remains.

Is the communication need to send and receive messages for one driver at a time ?

[MatthewM]

I notice from your topology drawing that you have specified a different Modbus Unit ID for each device.  Have you checked this is correct across all your devices?  I would not think it necessary to change this from the default 255, or maybe 1.