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Pi2 RS232 & RS485?

s-fly

I have a Fire Alarm Control Panel at home (I saved it when they replaced the system) and I'm wanting to use my Pi2 as a remote annuciator (RA). I also want it to log the printer port so I can view it online. The printer port is RS232 and right now I can log it from one of my computers via the serial port and TereTerm (its like hyperterminal but for win7)
I know RAs communicate with the panel via RS485. I tested this with my laptop and was able to find the the RAs send the characters back to the FACP (L = Acknowledge, M = Silence, N = Reset) I haven't been able to recreate this from my laptop because I don't know how to send from my usb-rs485 converter (I just listened to the com port via teraterm)

My main concern would be com port issues

 

Thanks in advance

 

(I found a expansion board called the RasPiComm but I only found one for sale and they are asking $70+ for it)

  • 0

    how were you testing it with your laptop, RS485 is not the same as RS232 so I am assuming you have a USB to RS485 adapter, if so then from the laptops perspective this is just another com port, it will not know the difference between serial TTL, Serial RS232 or Serial RS485

     

    do you know the protocol the alarm board is using ontop of RS485 ??, ie what commands you need to send in response to certain information ?

  • 0 in reply to Robert Peter Oakes

    Sorry, I don't know the protocol and I am really unfamiliar with RS485. I was using a usb to RS485 converter, here are some screenshots of what I captured on terraterm

     

    This is what I was seeing when connected to the RS485 out on the FACP (out to the RA):

    image

    and this is what I was seeing connected on the RS485 out on the RA (Back to the FACP):

    image

    I discovered that "L" was sent back to the FACP to acknowledge troubles. Also "M" was to silence alarms, and "N" was to reset the panel.  (There are only 3 buttons on these RAs)

    It looks like there data is sent every second, each trouble line from the FACP out and each "." from RA out. I'm assuming the "."s  are some form of data being sent back to the FACP because it monitors the circuit, and every time I connect to that port the "." changes to a different symbol. L,M, and N are the only constants.

     

     

    I hope this helps you figure out what I'm trying to do lol I will not that I'm away on a job and I won't be back till Wednesday so this project is on hold