Posts: 1
Joined: Tue Jan 12, 2021 9:43 am

Alarm Contacts

Tue Jan 12, 2021 10:07 am

Hi, I'm fairly new to rasberrypi and I'm looking for a solutions to measure and alarm on the output from a machine. The machine can provide a special cable to provide alarm signalling in the following format:

Alarm contact / Customer feedback contact

1 - Function

The machine cabinet is equipped with a set of potential-free alarm contacts at connection X1.

The contact (X1) is for remote alarm of the following malfunctions (pin 1; 2; 3;):
  • - Liquid level warning and alarm

    - ECU problems

    - Pressure (high/low)

    - Compressor stop

The Remote Alarm contact signal is reset to “Normal” when the acknowledge button of the alarm box is pressed and the audible alarm is off!

The contact (X1) is also for remote alarm of the following malfunction (pin 4; 5):
  • - Discharge Alarm
2 Connection details

Specifications for X1

Connector type HAN Q5 (6-pin)

Maximum load 230 VAC 6 A
not protected by a fuse

Code: Select all

Connector	Pin	Function(Indication)	State
X1		5	Release Alarm		Common
X1		4	Release Alarm		Normally Closed
X1		3	Remote Alarm		Common
X1		2	Remote Alarm		Normally Open
X1		1	Remote Alarm		Normally Closed
Where do I begin, I've got a raspberry pi and a bread board.

Any help/advice really appreciated. The goal here is to send an email/text message to notify when there is a problem.

I believe this is a HAN Q5 connector (I'm getting the cable this week). ... s/8430027/


Posts: 515
Joined: Mon Mar 19, 2018 1:18 pm

Re: Alarm Contacts

Tue Jan 12, 2021 12:52 pm

Find tutorials on how to connect and use simple push buttons with raspberry pi's GPIO

Those contacts you mentioned should behave just like buttons which your machine "pushes" on or off.

Regarding what every contact means ... you better link or attach real documentation, your description on what you understood of it is incomplete, sketchy, very probably inaccurate.

Posts: 660
Joined: Sun Dec 30, 2018 8:36 pm
Location: Denmark

Re: Alarm Contacts

Wed Jan 13, 2021 9:26 pm

This is a start: ... -computing

In essence you have two contactor pairs in your plug, one for when the alarm is turned on, and another for when the alarm is turned off.
If you are not familiar with normally open and normally closed and common, have a look here:
When there is no alarm there is a no connection between common and normally open, while there is connection between common and normally closed.
When the alarm is active the opposite is the case.

There is no potential in the plug, so you need to provide the +3.3V from the RPi to detect anything on the two contactors.
But have a look at the Physical Computing to better understand how you can setup the inputs, and then Google for a guide on how to send an email in Python.
Have fun!

BMS Doug
Posts: 4318
Joined: Thu Mar 27, 2014 2:42 pm
Location: London, UK

Re: Alarm Contacts

Wed Jan 13, 2021 11:14 pm

You will need to use two or three GPIO pins to monitor the signals.

X1 common fault is on wires 1 and 2 with the common connection on wire 3. (1 and 2 are the inverse of each other, when 1 is active 2 will be inactive and vice versa)

X1 discharge alarm is on wire 4 with the common connection on wire 5.

connect the common wires (3 & 5) to 3v3 and then connect the signal pins to your GPIO inputs.
I would use a set of 10k pulldowns on the inputs to eliminate false positives and connect an inline 1k resistor to each, to mitigate the risk of accidents. You can get a pre-made board that has the pulldown connections if you want to save yourself the soldering. ... stor-board
Building Management Systems Engineer.

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