New Mastertemp 250 gas heater - which is the RS485 connector?

[nothear2talk]

Hello,

I'm connecting my new MasterTemp heater to a DIY automation system (nodeJSPoolController) that handles RS485 communication with the heater (and my Intelliflo pump). After reading the Mastertemp manual it's not clear which connector is the RS485 port. After removing the heater's front panel, i see a 4-position screw terminal header on the upper left, and a 3-position screw terminal on the right. Which is the RS485? (note, photos are somehow mirror image).

Also the manual mentions 3 wires (black, green and yellow) but the pump uses 2 wires - green and yellow. I suspect black is ground an unnecessary.

see photos... if someone who has done this before could let me know exactly where i connect the green and yellow wires, i'd appreciate the help. I'd like to avoid blowing anything up .

thanks

 

[JamesW]

 

[nothear2talk]

Thanks. What is interesting is that on my heater, the 4-terminal RS485 port is on the left (typo corrected in my post)

 

[JamesW]

Thanks. What is interesting is that on my heater, the 4-terminal RS485 port is on the left (typo corrected in my post)

Looks like the same position to me.