Procedure for Verifying Registers

I work for a motor and controller manufacturer and my background is not controls. We produce a controller for our motor with various MODBUS registers consistent with normal VFD parameters although our controller is not a traditional VFD. We have a customer who has requested a procedure to verify the MODBUS registers are set for the parameters we have them as listed and I have been asked to develop the procedure or some type of test for verification of the registers.

Can anyone provide guidance or direct me to documents that would be helpful?

Thanks, John
1. It might be that the inquiry is requesting that you 'verify' your controller's Modbus map (as though the published version is not verifiable?).

I've used a copy of the vendor's Modbus register map (documenting with the source provenance) and itemized which values are read or written to. That level of documentation has seemed to fly in the past to the extent that no one has challenged its validity.

If someone questioned whether the published map was valid (a lot of what transpires in pharma validation is bureaucratic), I suppose I'd call the vendor and explain that their map is being questioned and ask them if they can 'certify' their map, probably by pasting it into an engineering drawing template and having the Engineering Director and a Quality Assurance person sign-off on it. A drawing with a signature goes a long way in the halls of bureaucracy. Not that such has happened, but it's where I'd start. Is this what the inquiry is asking - can you 'certify' your map?

2. If your controller has some form of HMI and that HMI has access to the same data as the Modbus registers, then it seems reasonable to assert that checking the Modbus values against the HMI readings would prove proper communication.
If you are looking for a tool that will read the values of the Modbus registers on your controller and verify them against predetermined values, this can be done with our free ICC Modbus Master Tool software available here:

To do this, you would create a profile (in XML format) that defines the register number and value for each parameter on your controller that you would like to verify. After you have created this profile, your customer can load the profile into the tool, connect to the device, and verify the Modbus register values.

We can also provide software customization services for the ICC Modbus Master Tool. We can skin the software to appear as your own, can have any XML profile be installed along with the software, and can have the communication settings pre-configured to connect to your controller.
Thanks for your comments. Yes, I think they are requesting that we certify our Modbus map. I'll check to see if we could get some type of signed engineering document.