Tstat7 modbus register help

sam · December 12, 2024, 5:41pm

I was hoping to get some clarity on the following specific items (on a Tstat7):
I need 4 basic items when I poll the device to report accurate status of what the unit is doing.

1) HVAC Mode (tstat setting):

I see register #101 (COOL_HEAT_MODE, heating or cooling mode. 0=none, 1=cooling, 2=heating)

Is this the correct register?

How can I tell if the thermostat is in Auto mode?

I also see regs 106/107 referencing modes but not sure what they do.

2) HVAC State (what is the tstat doing):

I see register #102 (MODE_OPERATION, heating or cooling state: 0-7 = coasting, cooling 1,2,3, heating 1,2,3)

When I poll 101 & 102 and get back : 0 & 0 I assume that means the unit is idle - right?

How can I tell if the thermostat HVAC mode is set to “Off” - can it even be set to off?

3) FAN Mode (fan setting):

I see register #105 (number of fan speeds or system modes,… Single speed = 1 up to three speed fan = 3)

I see it is always “1” which is indicating speed but not mode

4) FAN State (what is the fan doing):

Not sure what register to find this info… can you advise on this?

I have tried manipulating the device with the “Mode” button but it is not entirely clear what is happening to the above registers when I cycle through them.

Options I see on the Tstat7 device:

FANMODE: [ -AUTO- | MAN OFF ]

HEATCOOL: [ AUTO H/C | MAN COOL | MAN HEAT ] (register #101)

Thank you!

maurice · December 13, 2024, 4:11am

Could I ask you to spend a little time with the T3000 register viewer tool, this shows all the registers, their names and the current value. You can flip back and forth from the T3000 user interface and adjust the mode for example, and watch what happens to the register in real time. I will get Lijun to reply in more detail about the register questions above.

This long term plan for the Tstat7 is to port over the T3 programmable environment. We have already done this same process for the Tstat8 which is mostly superceded by the new Tstat10. This will give you a lot more functionality including user programs, floor plans, alarms and such. Unfortunately its a completely new set of modbus registers compared to the Tstat7. If you would like to switch your Tstat7 to a Tstat10 we can arrange that. The updated Tstat7 with programming features will be ready in 2-3 months.