Need help wiring an RCS TR16 Thermostat


Active Member
The instructions that came with my TR16 don't make any sense concerning the 12V DC power connection.

It states:

"Power Connection
The TR16 Control Unit can be powered by two power connection options.
1. External 12VDC power. Connect the 12VDC power transformer supplied to J4.
2. Power from the Communications Network. You can provide power to the TR16 Control Unit via the RS485 Network. Connect 12VDC to the RS485 Network terminals."

#1 - there was absolutely NO power tranformer supplied with the TR16 and 'J4' has no plug/jack on the board--not used.

#2 - the diagram shows 4 terminals for the RS485 Network Connection at J3 [12V, GND, D+ and D-], but on the actual control unit the RS485 terminals are on J2 and there are only 3 terminals--no 12V!

Am I missing something?? Where am I supposed to run the 12V to from my RS485 connection?
<ToyMaster> I just got a TR40 to replace my TR16
<jeffx> did they ship me the wrong CU??
<ToyMaster> The Tr40 is the same way. You do not need the positive to connect on the RS485 bus
<ToyMaster> I double checked that today with RCS
<smee> the manual shows that the connector for the rs485 should also have conntacts for power.
<jeffx> where is it going to get power from then?
<bravesirrobbin> on page 20 smee, that's where i was looking?
<jeffx> the manual does not match the CU.
<jeffx> it was originally back ordered, so it's the latest revision
<ToyMaster> the power comes from the HVAC system
<bravesirrobbin> 12 vdc?
<ToyMaster> 24vdc
<jeffx> seriously? does it convert the 24v?
<ToyMaster> yep
<gordon> did they perhaps combine ground and negative or something?
<ToyMaster> thats why there is a big transformer on it
<jeffx> that is odd--from the 24VR connection?
<ToyMaster> since no power is needed from the RS485 bus for the unit it only needs the negitive and 2 data
<smee> Maybe the manual is out of date?
<jeffx> it would have been nice of them to update the instructions--I can only imagine how many calls this will generate.
<ToyMaster> then it takes the power it needs from the 24vdc running on the HVAC system
<bravesirrobbin> ah, on page 25 for the TR16 control it does say "optional 12 volt power input"
<ToyMaster> it confused the crap out of me too
<smee> However, on page 21 it says "Use only ONE power option! Do not connect the communications network power connections to a powered hub if you are also using the power transformer."
<jeffx> on the tranformer, "24V 60Hz, 12.6 V/200mA, 6.3V/400mA"
<smee> It sounds like the communications network power connection is no longer present on the board.
<gordon> tha'ts quite a "revision".
<jeffx> I'd say.
<jeffx> thanks ToyMaster, you just helped prevent a sleepless night
<ToyMaster> they first did it on the zwave model then adopted it to the rest of them
<ToyMaster> I have 6 to install tomorrow so you got lucky that I brushed up on them today
One note to add. If you may have to run an extra wire from the HVAC unit to the CU for the 24V Common connection.
Yes, I did have to run the Common wire to power the CU. Had everything connected and configured in HAL this morning. Working great!

Thanks again for the assist. My wife really likes the sleek look of the TR16.
There was a major update to the hardware but the setup document was not updated.

The TR16 no longer requires a 12V power source as it uses the 24V feed from HVAC Common and converts it to 12V.

I recently ordered a TR16 thermostat to go with my Stargate SG-IP and the kit came with a CD and a Quick Start gide that showed the new power wiring configuration.

Who did you get your kit from? It is strange that it did not come with the updated Quick Start Guide.

purchased from Smarthome for $135 during their 25% off promotion. It was on back order for about 1 week, so it was probably the very first batch with the hardware update.