Bypass using an Aprilaire 8811???

[HaLo6]

I have a Aprilaire 8870 and a BlueHeat RS485 / RS232 Serial card... is it possible to hook it up directly to that? What exactly is the pinout for the 8870? On the Tstat there is A+/- and B+/-. How do those correspond to a typical RS485 DB9 pinout? Any help would be awesome!

 

[dBeau]

I have a Aprilaire 8870 and a BlueHeat RS485 / RS232 Serial card... is it possible to hook it up directly to that? What exactly is the pinout for the 8870? On the Tstat there is A+/- and B+/-. How do those correspond to a typical RS485 DB9 pinout? Any help would be awesome!

Yes, it's possible. I have not used the BlueHeat card, but I have used a Neteon GW312 serial to ethernet device. The GW312 works great, BTW.

As for the pinout, I dont know if there is a standard mapping of RS485 to a DB9, but page 22 of the BlueHeat's owners manual shows the pinout that it uses. Their labeling is a bit confusing but it looks to me like pins 1 & 4 would connect to A+/A- while pins 2 & 3 would connect with B+/B-. Their diagram does make it clear that 1&4 are the receive pair while 2&3 are the transmit pair. On the 8870, B+/B- are the receive pair and A+/A- are the transmit pair.

 

[HaLo6]

Awesome, I saw that in the manual as well, just wanted to make sure I was going down the right track! thanks for the help!