jeditekunum
Active Member
The Carrier (SYSTXCCNIM01) or Bryant (SYSTXBBNIM01) NIM (Network Interface Module) interfaces the Infinity/Evolution systems to ventilators and/or non-Infinity/Evolution A/C. I picked up a reasonably priced Bryant NIM on eBay and connected it to my Carrier system and it works fine (be aware that older Infinity/Evolution thermostats don't support any NIM!).
The ventilator interface is labeled B, G, R, Y:
B is ground.
Y is +DC sense.
G is control.
R is unknown at this time.
Y must receive positive DC voltage from the ventilator in order for the system to recognize that a ventilator is attached. In my case +12V works.
The NIM places a resistance between B and G terminals to control the ventilator. My test results (with an ohmmeter) are:
357: high
4K: low
22K: off
As I stated in my prior post about the ventilator, these resistance values are not consistent across all systems. The Broan ERV that I have does not work correctly when directly connected to the NIM.
I will be building a home-brew translator circuit. At first I thought a couple of relays and some analog comparator and logic circuits would do the trick. I'm now thinking that I might go way over the top and use a small microprocessor with ADC to measure the NIM side and a digital potentiometer to drive the ventilator. Any suggestions welcome!
The ventilator interface is labeled B, G, R, Y:
B is ground.
Y is +DC sense.
G is control.
R is unknown at this time.
Y must receive positive DC voltage from the ventilator in order for the system to recognize that a ventilator is attached. In my case +12V works.
The NIM places a resistance between B and G terminals to control the ventilator. My test results (with an ohmmeter) are:
357: high
4K: low
22K: off
As I stated in my prior post about the ventilator, these resistance values are not consistent across all systems. The Broan ERV that I have does not work correctly when directly connected to the NIM.
I will be building a home-brew translator circuit. At first I thought a couple of relays and some analog comparator and logic circuits would do the trick. I'm now thinking that I might go way over the top and use a small microprocessor with ADC to measure the NIM side and a digital potentiometer to drive the ventilator. Any suggestions welcome!