Interfacing with Paradox Spectra 1738

I got a Paradox 1738 Spectra v2.10 Alarm Panel that I need to interface with.
Thanks to the info found in this thread:

I managed to interface directly on the serial port @9600 bauds. Other users seems to get 37 bytes packets, but in my case, I only get 4 bytes/event.

Think I decoded part of it correctly, but is there more info on that 4 bytes version of the Paradox serial protocol?

Updating the thread in case someone else encounters this version of the Paradox protocol.

I managed to get what I needed of of it by walking the zone and setting off the alarm on purpose.
Still to be done would be analysing the Status 1st byte… but all I need for now is keeping a log of events + reports of alarms/watch some users lock/unlocks.

Hi MarioT,

thanks a lot for sharing this information! I have a Spectra 1728 and have just started to log the packets, and you helped a lot on how i can decode them.

also thank you for sharing. I have Spectra 1738 too. I am going to do something with it but had no time yet. However, your info could be useful for me. Thx.

I have a Spectra 1725EX v1.20. I was hopping to use MarioT's findings to read logs out of this panel. Unfortunately, 0x00 and 0x04 packets (zone open and close) are never sent from the panel, while others (like arm and disarm) are. These were the two most important logs I was hopping to read. Now I will have to replace my old security panel to a new one are reprogram it and I was hopping to avoid this process.

I wonder if anyone has any additional info about the old Paradox serial protocol that he/she could share? Does it allow only receiving data? Is it possible to request panel's current status?

By the way, when you enter programming mode and exit it 0x78, 0x41 and 0x78, 0x51 are being sent.

My Paradox 1738 Spectra v2.10 Alarm Panel gives 7 bytes on open/close. Anyone have decode for 7 bytes ???