Trent .... I really need your help regarding the PC Alarm and keypad.

EPE and SiliconChip don't really seem to be able or willing.

I have built both.

I made a custom serial cable with only the tx, rx and earth connected for the PC comms. This goes direct to the 3 way block on the main PCB. I was having an issue with the 'standard' serial cable I had (that worked with the Serial IO Controller) going via the front D socket. I'm not sure why, but I never got a connection working (all connectivity was checked and fine).

The PC software works but seems very intermittent ... sometimes the alarm responds to commands, other times it doesn't. My gut feel is there is a handshaking problem somewhere down the line.

I then built the keypad. When connected to the front dpad the LED comes on and you get a crescendo tone indicating power up. I set up codes for each of the 4 users in the Zone Config GUI and the Tx / Rx light came on when OK was hit suggesting they were being sent to the PIC.
When I hit a numeric button on the keypad (PC serial cable disconnected from PC), you get a single beep. When you hit arm or disarm ... you get 4 beeps like a D D D D. I never see the Tx / Rx light flicker suggesting no comms ... and I never get a different arm / disarm tone regardless of whether I put the right or wrong code in.

It strikes me that the PICs are not communicating. I have tried two 4Mhz crystals in the main alarm and 2 in the keypad thinking maybe that was causing one not to be talking at 2400 baud. I also tried programming both PICS with Oscillator mode of XT and HS. I'm pretty sure HS is what is needed for 2-4Mhz and that is what they are both currently programmed with.

As I say .... I've checked all connections, particular those with ribbons in between. In all cases I've taken the connection from the source component to the destination component (eg PIC16f84a output to PIC16f877a input .... and they are all perfect.

I'd hugely appreciate any diagnostics suggestions you may have.

Best regards

Paul