NI 9871 modbus card not working

[David99999]

Trying to talk to a device and I'm not able to establish a modbus TCP connection to the slave. Referencing this link, Using I-9871 with CompactRIO , I THINK I have everything installed.....the only software I'm not seeing on my cRIO is what they are referring to as NI-Serial RT. 

I'm using a CompactRIO 9053 and LabVIEW 2020. I am able to talk to the modbus slave from laptop via Python, so I know my settings such as the port are correct. My cRIO's ip address 192.168.2.23, and my slave is 192.168.2.250, so I'm on the same network.

Below is a screenshot of what is installed on my cRIO. There's more if you could scroll, but they aren't related to the serial issue I'm having. Like I said, everything required seems to be there except for NI-Serial RT but that doesn't even show up anywhere on the Add section.

[David99999]

Alright sooooo........should I be going out of the cRIO's main ethernet port instead of trying to use a 9871 card, since I'm trying to communicate with modbus TCP? Is the 9871 meant only for serial such as RTU?

[santo_13]

If you're looking for TCP, a regular cRIO Ethernet port should work. I don't think the Modbus card would support regular TCP.

[RTSLVU]

Modbus TCP is simply put, "Modbus over Ethernet".

No special hardware beyond an Ethernet interface should be needed.

Modbus RTU is serial and usually requires an RS-485 (most common) or RS-232 interface.

These are most often a simple USB to RS-XXX device that installs a virtual Com port.

[JensG69]

Just to clarify, the NI-9871 is a card with up to 4 serial ports (RS-422 or RS-485). It can be used to talk to a modbus device with a serial RS-485 or RS-422 interface. But it is not limited to the modbus protocol. It can be used with any serial protocol.

Regards, Jens