Build own DB9-RS485 wire? Connect them to Elk

[Sendero]

I've been trying to find info on this online but only seem to find $40 adapters for RS232-RS485. I have a new TR40 that is installed a working fine. My Elk isn't setup yet but I want to verify communication with the TR40. Are there wiring diagrams for a adapter to go from a DB9 serial port to the RJ45 RS485 connector on the TR40?

Also, once I get the Elk setup, how do I connect it up to the thermostat. I already have the serial port expander but since the thermostat is RS485 can I just hook it up to the Elk's DBH and have it work?

 

[Steve]

Also, once I get the Elk setup, how do I connect it up to the thermostat. I already have the serial port expander but since the thermostat is RS485 can I just hook it up to the Elk's DBH and have it work?

No, it needs to hook to a serial expander, thats where the firmware is. Read the manual for hookup instructions - page 7.

 

[Sendero]

Also, once I get the Elk setup, how do I connect it up to the thermostat. I already have the serial port expander but since the thermostat is RS485 can I just hook it up to the Elk's DBH and have it work?

No, it needs to hook to a serial expander, thats where the firmware is. Read the manual for hookup instructions - page 7.

Thanks for the confirmation. I had seen that in the manul but since they were both RS-485 I figured i'd give it a shot Oh well, glad I already have the expander.

Any info on if its possible (and how) to make your own DB9->RJ45 cable that will allow me to test out the control of the TR40 from my PC before I get my Elk in and connected? Or do I need to buy one of those adapters I've seen online.

 

[DavidL]

You need a RS232 to RS485 adapter in the mix. I happen to have a 8 port RS485 RCS one available, but in your situation, I would wait for the ELK connection.

Once you get electrically connected correctly, you would still need software on the PC to connect to the thermostat and allow you to issue commands.