ELK-M1DBH Odd Behavior

Hey all,

I have an ELK M1 Gold with ELK-M1DBH Data Bus Hub. I have 3 M1KP2 Keypads, a ELK-M1XIN 16 Zone Expander and a ELK-M1XSP Serial Port Expander.

The keypads will only properly enroll when attached on the data hub to postions 1, 2 and 3 respective to thier addresses. For instance, if I move Keypad 1 to position 3 none of the keypads will enroll.

If the keypads are properly matched to the correct positions, the Zone or Serial Expander will both work in position 4 but neither will work in postion 5 when the other is attached in front of it.

None of the devices are teminated on the device, the JP3 is in place on the M1 as well as the terminating plug on the data hub. I've tried changing device addresses to no avail. For some reason I cannot get all 5 devices working at the same time!

Does anyone have any suggestions?

Thanks!

Check your wiring. Sounds like a bad RJ to me.

Checked all the RJ's. Everything looks good. Every one of the components work when plugged in, just not all 5 at the same time! I'm getting power to everything, the LED's are lit, the 5th device just will not enroll. I'm baffled!

It's most likely a wiring issue (or less likely a bad hub, device or cable), like DEL said you probably have a questionable termination somewhere. The hub is not active like a network hub or switch, it is passive and daisy chains the wiring one to the other. So if you insert a flaky termination in the wrong place the signal just ends up being too weak to work. Power on a device is not necessarily going to indicate a good termination of the signal wires.

You could try to plug/unplug devices and look for bus errors incrementing and maybe narrow it down. But take a good look at your terminations and see if any look unusual, RJ45 and the xsp/xin,reterminate the RJ45's one at a time, if that doesn't help then you need to investigate your in wall keypad terminations as a last resort.

I suppose there might be a way to hook in a multimeter and maybe measure the bus resistance and see if plugging in one of the devices makes it jump or something to determine the bad termination. Not sure what that should normally be or the limits are though...

Del & wuench, thank you both for your help and insistence that it was a wiring issue! You were 100% correct, I went back and triple checked my RJ's and sure enough there was one wire which I failed to push completely to the end of the connector on one of the keypads that has been in place for years! It was never an issue until I started adding the expanders.