Hi All,

I am having a problem setting up a DT80 as a Modbus slave on the RS232 port, and I think it may be because the profile settings are not being used properly, if at all.

Every time I try to load a job, the PROFILE commands seem to be ignored and I get the following error message: Invalid PROFILE section/key name at column 53 [ _OLD_DATA'<err> ] I have done DELALLJOBS and FACTORYDEFAULTS to try and clear things out, but the problem persists.

Having said all that, I have tried setting up the host port manually using PROFILE "HOST_PORT" "FUNCTION"="MODBUS" etc, and the config appears to change but I still can't get any response from the dataTaker using a Modbus master simulator on my PC.

Any thoughts, anybody?

Regards,
Robin

Good morning Robin,

Did you reset the dataTaker with singlepush command after changing the profile settings? Any changes to profile are loaded after the dataTaker is reset.

Cheers,
Roger

Hi Roger,

Thanks for your reply. I did SINGLEPUSH every time, but it didn't make any difference - the error persisted...and then, when I tried it one last time, it went - I am not sure what changed - I wonder if there was a stray space in the code or something like that?

Anyway - my Modbus problem still seems to be a problem. I am using a Maple BLU300 HMI as suggested in the 3rd-party products section. The BLU300 works perfectly when talking to my PC running a Modbus slave application, but I can't get any response from the DT80 (firmware 7.02, I think).

I also get nothing from the DT80 when I run a modbus master application on my PC. It is probably something stupid, but I've run out of ideas.

Regards,
Robin

Hi Robin,

It's probably a setting then. Let's start with the communications first, then we'll look at the program.

How are you connecting the HMI to the DT80? What are the comms details for the HMI? What have you changed in the profile?

Cheers,
Roger

I, being the Devil, or at least her advocate, suggest it is probably one of the really simple things causing the lack of Modbus talkies.

• Address
• Baud Rate
• Modbus Function code used.
• Register being requested.

The DT80 manual has a good run down on using Modbus, including a debug parameter you can use (P56) to check the actual serial traffic.
Example:
Modbus RX <HOST: 01 0400000008f1cc (8)
Modbus TX >HOST: 01 041000000000000000000000000000000000552c (21)

Roger, Craigus,

Thanks for your suggestions - I have it all working beautifully now. It turned out to be a faulty cable - I've never had one of those before so didn't think to check.

I can confirm that the BLU300 works very well!

Regards,
Robin