Elk M1G Data bus

[mohansen]

Is it possible to extend the RS485 databus to a seperate panel and then have multiple modules installed on the remote panel?

I have a M1G with several keypads, IO cards, etc. configured. I have a separate building being built that would have keypads, IO, etc in this new building. I want to extend just the databus and put the additional modules, keypads, across one RS485 connection instead of having to run 10's of pairs of cabling back to the M1G. I have a data bus hub on the M1G today and would like to put another one at the remote panel and use one RS485 connection between the 2.

The RS485 bus should be able to go the 300' distance without problem.

Has anyone tried this or see a reason it won't work?

 

[Digger]

Is it possible to extend the RS485 databus to a seperate panel and then have multiple modules installed on the remote panel?

I have a M1G with several keypads, IO cards, etc. configured. I have a separate building being built that would have keypads, IO, etc in this new building. I want to extend just the databus and put the additional modules, keypads, across one RS485 connection instead of having to run 10's of pairs of cabling back to the M1G. I have a data bus hub on the M1G today and would like to put another one at the remote panel and use one RS485 connection between the 2.

The RS485 bus should be able to go the 300' distance without problem.

Has anyone tried this or see a reason it won't work?

It should be fine but remember that you have to be careful of transients etc.

 

[rfdesq]

Are you going to tie directly off of the M1 or are you going to use the last unused output on the DBH to feed the other DBH?

 

[mohansen]

I can do either one. My original thought was to use a port off of the DBH.

 

[Digger]

Count on using an additional power supply with its own battery backup. Tie the negative of the 4 wire buss and the additional power supply together. You will not use the power from the panel itself and this will minize a voltage drop as well.

 

[rfdesq]

I can do either one. My original thought was to use a port off of the DBH.

If you use a port, don't forget that the Cat X cable you make is a crossover cable.

 

[murphy]

Hi Morris,

yes, no problem.

You can use the RS485-bus between the 2 locations this way. This is one of the advantages of a RS485-bus. The reach of the signals is even longer. Maybe you run into difficulties with the 12V-power on the bus if you are using a lot of power at the far end (, -if the voltage will drop below 10 V ?). In this worst case, you can add a 12V powersuply at the far end. I think, with your equipment, sure no additional powersuply becomes neccessary.

In my application, there are also two locations connected with a RS485-bus. Only around 100' away. At the far end there is a keypad, an output-relais-card and an input-card. The connection is running via an old buried thermostat-cable. This has thicker wires as usual CAT5 but is not twisted as CAT5 or so. In every case it is working clean. A RS485-bus is rather robust.

In a wiring-diagram of the "M1-Installation and Programming"-Manual, on page 7, there is a remark: max lenght of the RS485-bus should be 4000 ft.

 

[mohansen]

Great information. Thanks for your help.