Elk M1 Received, need help with EOLR + Serial


Active Member
Hey --

I did a search, which extolled the need for the EOL resistors. However, is there a special way in which to install them? eg: is one side negative and the other positive?

For a bench test, I installed all the provided EOL resistors into zones 1-16, connected the speaker + power, and when I turned the unit on, the KP reported some of the zones weren't ready. Then it changed its mind. The EOLRs are all tightly screwed down, but it seems to me that the little plastic piece they connect to doesn't seat very well into its slot, and that small motions Not-Ready some Zones that were Ready before, and vice-versa.


Also, how does one use an EOL resistor on a set of door sensors? I don't see anyplace obvious to solder... do I need to T the wires (sensor + EOL + cable back to ELK)?

Final question... my dell has a serial port. I forced it to run on COM1. I have a modem that's on COM3. in the Communications menu, ElkRP only has COM3 in the list box. Do I need to disable the modem?



There is no polarity on resistors. As far as the keypad changing its mind, sometimes motion sensors have to initialize before showing correct state.

It has been a while since I used the Elk software, but I thought you could select which com port you wanted to use (in your case com1).

Make sure nothing else is competing with the port (handheld device for instance).

As far as installing EOL's I would just solder them as near to the end of the sensor as possible, then shrink wrap the entire connection. Let's see what others do here for more ideas.


Staff member
Does COM1 show up when trying hyper terminal? I believe COM1 and COM3 share resource, so disabling the modem might help. Also, has this port ever worked before? Maybe it's disabled in the BIOS.


Senior Member
If you searched here on CT I think you would have seen the vast majority of people saying they are not needed on an M1. But if you do use them, make sure they are at the sensor, not connected to the M1 directly. That would truly be a waste.


Senior Member
If you do not want to put up with the pain of End of Line resistors, go to the zone definition, hardwire selection and make the zone normally closed. Then you do not need the EOL resistors.

Upon powerup, there is a 6 second time period that the M1 waits for all the zone inputs to stablize before the system is usable. During that time you may see zones show up as violated then restore.

You should not be able to wiggle the terminal strip plug-in and cause a zone to violate. Make sure it is pressed down into the socket all the way. If you continue to have this problem, call ELK technical support about it.

ELKRP scans the computer for usable serial ports and lists them in the drop down box. If Com1 is not showing up, it is probably already used. Com3 attached to a modem could be showing up because the modem is not using the serial port.