Based on your Modbus Poll screenshot, I’m pretty sure you should have one-based addressing checked, but Modbus is always fiddly.
Groov will put a 40 in front of your address when you save it - that is just a dumb way to let you know it is a holding register.
Yeah. I don’t disagree, but I was overruled way back when.
First off - I’m not sure the groov can write to the individual bits in an address or you need to figure out what the complete 16 bit string is. So perhaps ‘stop’ is a ‘1’ at bit 0 in the 16 bit string (0000000000000001), ‘Menu+’ is a ‘1’ at bit 7 in the 16 bit string (0000000010000000).
If you want to do bit addressing, configure your tag as a Boolean, not an Integer, and point it at a Holding Register, like this:
I’m assuming your target device doesn’t have any sort of logging available, right?