Controlling a relay remotely via 2 Motorola Radios.

[kc_hubbs]

I know I had a previous post that somewhat related to this, but I figured this warranted a new thread.

I have a collection of Motorola Cm200's and Pm400's.

Im wanting to be able to control a relay in a building from a piece of heavy equipment. We have this set up right now using external encoders, and decoders. However, we have some new pieces of equipment coming in and in reading, I found that the Cm200s and Pm400s support their own encoding/decoding.
The radios do not support decoding of DTMF, however they do support MDC and Quick-Call II. Would I be able to use this ?

 

[W4WMH]

I think those radios support encoding of DTMF, and you could use this board: Intuitive Circuits, LLC. - DTMF Decoder and DTMF Encoder Products for Relay Controls .
Connect that board to the audio out of a radio sitting in the building, and program the CM200's with BOT / EOT DTMF. Set a channel in the transmitting radio to send the DTMF string that would trip Relay 1, and call that channel "Relay 1" or "Door Open" or whatever.
I've done the same at home. Flip to a channel in my radio, on a lesser used channel, key up, and all the driveway lights, exterior lights, etc are flipped on for 20 minutes.

And just FYI, I think if you want to turn the relay on and off, this would be 2 functions, and require an external board. The Mobile radios I've used all only have 2 functions in regards to SelCall / QC2 / MDC / DTMF Paging; Call Alert (make noise break squelch to hear message), and Transpond (do the first one, and Transmit back a tone to call in that you received it, without the user doing anything). So using the internal encoders / decoders would probably only let you turn something on, OR turn it off, but not both.

Just putting that in there for your consideration.

 

[kc_hubbs]

In our situation the relay controls a safety system. So it would only need to be activated 1 time. We wouldn't be turning it off.

Do these radios only transmit the DTFM code 1 time, or would it be as long as the button is pressed down ?

 

[W4WMH]

They transmit the code 1 time when you key up or let go of the PTT, depending on whether you use Beginning of Transmission or End of Transmission.

 

[kc_hubbs]

Thanks so much. This system is somewhat in place now, but we are tying to add to it, and possibly get rid of all external encoders/decoders.

However, for the time being, is there a way to find out what the DTMF code is from a encoder or decoder ?

 

[prcguy]

If the radios can send a DTMF string here is a good DTMF decoder board I've used. Its programmable for 1 to 7 digits, has momentary and latching outputs and other features. ST-809B Miniature DTMF Decoder New Product Bulletin

 

[prcguy]

There are free DTMF decoder programs you can download then feed the audio to the computer running the program to decode the string. Or I have several decoders with a display that will take in speaker audio, etc.

Thanks so much. This system is somewhat in place now, but we are tying to add to it, and possibly get rid of all external encoders/decoders.

However, for the time being, is there a way to find out what the DTMF code is from a encoder or decoder ?

 

[kc_hubbs]

Im in an office pretty far away and only have access to one of the radios with the encoder on it. I guess theres no way to have the DTFM code come out of the radio its self when it transmits ?

 

[prcguy]

Download the free decoder program into your office computer then use a police scanner to receive the radio and feed that into your computer sound card in your office.

Im in an office pretty far away and only have access to one of the radios with the encoder on it. I guess theres no way to have the DTFM code come out of the radio its self when it transmits ?

 

[N5XPM]

Download the free decoder program into your office computer then use a police scanner to receive the radio and feed that into your computer sound card in your office.

I worked on a system where we used the DTMF encoding / decoding on CDM 1250s. I drove a simple automotive type relay with the output from the Expanded Accessory connector and in turn drove a latching relay with the relay output (which is sort of a "toggle" relay but could switch 120 volts with a few amps), which turned the "circuit" on and left it on until the transmit radio sent the DTMF code again, turning the circuit off. Might have used QC II, but DTMF was faster.

 

[kc_hubbs]

I'll try one of those decoder programs. I found a few Android apps as well.

Is this possible with QSii ?

Can this be triggered by a connected mic, or does it have to be a button connected to the external mic pins ?