PLC5 PCCC type client not able to read N type register

[Mrudula Chougule]

Hi,

I am running RTA server configured for PCCC type protocol on Ubuntu 20.04. I tried using the plc5 sample application available in libplctag c/c++ package over ethernet ip.I am getting below errors,

ERROR PLCTAG_ERR_REMOTE_ERR: Could not create tag!

Please suggest the correct sample application/ steps to read the N type register over ethernet ip from RTA server.

Thanks,

Mrudula

[Kyle]

I looked up RTA.  They have several gateways.   What model is yours?   The gateway translates some sort of protocol on Ethernet to what looks like DH+ on the other side.   I need to know which protocol is on each end.  Is this like a DHRIO module in a ControlLogix?  Or does it have mapped data files like a Control/CompactLogix can do but still use the CIP protocol?  There are many possibilities:

1. A Ethernet/IP to DH+ converter.  This is what a DHRIO module does.  
   
2. A Logix-class PLC that supports mapping tags to PCCC-style data files. 
   
3. A PLC/5e that supports the Ethernet/IP protocol directly.   PLC5e with updated firmware can do this.

It it is 1, then you can use DH+ bridging with the PLC5 PLC type.  Example:

tag_rw2 --type=uint8 '--tag=protocol=ab_eip&gateway=10.206.1.40&path=1,2,A:27:1&cpu=plc5&elem_count=1&elem_size=2&name=B3:0/10' --debug=4

  

If it is 2 you can use the logixpccc PLC type.

(looking for an example)

If it is 3, you can use the plc5 PLC type.

tag_rw2 --type=uint8 '--tag=protocol=ab-eip&gateway=10.206.1.38&plc=plc5&elem_count=1&elem_size=2&name=B3:0/10' --debug=4

Best,

Kyle

[Kyle Hayes]

You can find the API documentation on the web site here.

Best,

Kyle

On Wed, Mar 12, 2025 at 6:59 AM Mrudula Chougule <chougul...@gmail.com> wrote:

Hi Kyle,

Thanks for the detailed information. I used plc5 and it worked. I can read N type registers now. Do you have API documents that I can access for like plc_tag_get_int16(), plc_tag_get_float32(). I am not getting the correct results so I dumped data packets and could see it is working fine. Also can you share the details about client that can be used to query the CompactLogix type PLC, please? I am planning to add the support for Logix type PLC on RTA side.

Thanks

Mrudula

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