MOTOROLA CM140

#102 Reprogramming an old CM140 radio

Motorola CM140 From 2003.
Testing shows great results.

If you do not have the code plug password or a saved code plug with the radios serial number then this post is for you.

I recently came into possession of 2 Motorola CM140 25W radios. These radios belonged to my grandfathers old security company which is now dissolved, however amongst a lot of the kit I was able to save a few gems.

Upon inspection these radios were in immaculate condition despite there age. I was able to power up both radios only to find that they were programmed to one channel and when I used Commercial Series CPS (customer programming software) I could not read or write to the radio since the code plug was password protected.

Luckily I found a sample code plug for the model of CM140 radio I had. This allowed me to clone and change the password of the radio using the sample code plug now I can read/write to the radio

I have created a step by step document on my GitHub page here.

Schematic For The Programming Cable. Updated to V1.1 on the 3rd of April 2025
Any 5v TTL Device Can Work.

12 thoughts on “MOTOROLA CM140”

    1. Hocam ch340 usb alıyorsun. Bu yukardaki bağlantı şemasında sadece gnd rj45 te 4 gösterilmiş 5 olacak. Çalıltırdım sorunsuz

  1. Greetings!
    I think that Pin 4 and 5 on the RJ45 connector should be swapped in the schematic (Gnd to Pin 5).

    Anyway, thanks for the Post!

    73

    1. Hi there,
      Thanks for the comment.
      It should be correct.. worked with mine in that configuration.

      Though I took it with a grain of salt.

      1. With the cheap FTDI -TTL from China your system worked fine. the 1k R between 8 and 6 was needed tough I did not measure 1k at the original working programming cable I borrowed and opened to see what is inside.
        The CPS program here is version R05.16 I could use comport 7 most ports in the range 1-16 are occupied here I tried com40 but that did not work , I think you have to use the low range 1-16 ports for CPS I think. Older programs some times can not use comports above 16

    2. I can confirm
      RJ45 pin 5 is ground
      In the original Motorola cable RJ45 pin 5 is connected to D9 pin5
      ground at both ends
      And D9 pin 2 TxD and pin 2 Rxd are connected 3 wires needed at the PC comport side only
      The Motorola D9 contains a small pcb HEF4093 and an 78L05 plus some transistors resistors
      data rx /tx seems combined over one line by this circuit . Bi-directional that can also be done with a diode and resistor as in the circuit above . I found that data transfer worked even without ground some time but ground is needed

  2. Salve, desidero sapere se posso utilizzare il cavo programmazione del Motorola GM340 per programmare il Motorola CM140, grazie.

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