DINT and Modbus Adressing

Good nigth for everyone,

I’m using a Rockwell Micro850, and I adressing it in ignition via Modbus TCP, but when I try to create a DINT tag I can´t addresing it in Ignition. Please, someone could help me.


Hi John,

In Ignition have you tried using the Long type which is Int8 (8 byte integer)? :slight_smile:

By happy coincidence, I use a few 850s around here. :slight_smile:

Here is an example:

###Modbus mapping on the Micro850:

###Ignition Tags:
Note: This particular application uses unsigned integers (HRUI). Use HRI for signed integers.

Thanks for that. I had the exact same issue with Micro850 and your post was “spot on”.

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Were you able to get it to work? I’m connected to Micro820s, but the HRUI code doesn’t work for me. It will see HRUI1 as incrementing by 65k (16 bit) and then HRU2 as incrementing by one, but looking at the same tag. The only way I can get values is to use HR1 for the first address and HR3 for the next tag, and then only get INT not DINT values.

Looks like maybe the HRUI is broken? At least as far as communicating with the Micro800 series is concerned.

HRUI is a 32-bit value, which means it has to read 2 registers. Given that, it should be obvious that to have 2 consecutive HRUI values they would have to be e.g. HRUI1 then HRUI3 otherwise they would share an overlapping register.

If you’re seeing weird results your addresses might be off by 1 or you may need to toggle the zero-based addressing setting.

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Thanks for the tip. Your response got me looking in the right direction.

I needed to set Reverse Word Order in the advanced properties :slight_smile: