ELK M1 Databus Issue/Impact

[russr999]

Hi All,
 
Question (might be a dumb one)...:blink:
On the ELM1 there point out The RS485 Data Bus must NEVER have more that two (2) terminating jumpers installed.
What issues would I see if I had more than 1 terminating jumper on each home run?
 
I recently discovered that both my home runs had more than 1 terminiating jumper. Apologies, as a new poster I cannot post a link a picture of the alyout.
On Homerun1 there are 3 keypads with the last 2 keypads having the terminiation pin on JP1 and on Homerun2 there are 2 M1RFTWM and both have the termination pin on JP1
 
 
Any/all help appreciated. ray:
 
Thanks

 

[RAL]

Having a few too many terminators won't harm the data bus, but it may make it less reliable, or keep it from working at all.
 
When the data bits are sent out on the wires, they need to arrive at the destination with as little distortion as possible. Properly terminating the data bus with just one termination resistor at each end helps ensure that they do.  If you have the wrong termination, the signals become distorted or can reflect back down the wire and cause interference.  Whether the interference causes trouble or not can depend on many factors, including  the length of the cables.