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BRIX NetAlarm uses existing infrastructure to quickly send alerts such as panic alarms or fire alarms to computers.

With a press of a key, users can quickly call for assistance.

Alert others with a key press

 

Additional wired and wireless accessories can be connected, such as panic buttons, door magnets, motion detectors, smoke detectors and many more.

Wireless alarm button
Build your own pear push button PDF  | Print |

This guide shows how to connect a commercially available standard pear push button to BRIX NetAlarm. You can of course substitute the pear push for another wired emergency button, pull cord or basically anything that gives you a simple normally open (N.O.) contact.

Tools

You will need a pair of wire cutters, a soldering iron and a screw driver.

Parts

  • Pear push button or other type of emergency button with a normally open contact.
  • 9 pin female D-SUB contact for soldering, including a cover
  • 4,7 k resistor

Parts required to build a pear push button that can connect to BRIX NetAlarm

Preparing the button

Use the cutters to get rid of any prefitted contact, then peel off the coating from the wires.

Getting rid of prefitted contact and peeling the wires

One of the wires may be red, like this, but it doesn't matter what colours they have. If the button is just a closing contact, it has no plus or minus and it doesn't make any difference at all which colour goes where. And if the button is not a simple closing contact, it won't work anyway.

Soldering

Now add some solder to the peeled wire ends to make it easier to fit them in the D-SUB. Solder the resistor to the centre pin of the D-SUB (pin number 3). Then slide a piece of isolating PVC tube over the resistor, and bend it so the other end of it can be soldered to pin number 1.

Solder the resistor to the centre pin (number 3) and put some solder on the wires

The wires from the button should be soldered to pin 4, and pin 1 (together with the loose end of the resistor). You should end up with something connected like this:

NetAlarm external trigger via RS-232, circuit diagram

Pin 1 is DCD, pin 3 is TxD and pin 4 is DTR.

Covering up the mess

Finally, it's time to fit the cover on the D-SUB contact. Remember to use the cable strain releif brackets that come with most of these D-SUB covers, they will prevent the user from tearing your beatuiful solder joints apart.

Finally, put the D-SUB cover on

If all went well, you should now have something looking like this:

The completed pear push with D-SUB RS-232 connector

Now you just need to find a COM port where you can plug it in. If you don't have one, you could of course use a USB adapter. It works most of the time, but it is definitely less stable than a "real" COM port. Also, it's a lot easier to accidently pull out a USB plug than it is to pull the D-SUB out, in particular if you have fastened the screws on the D-SUB.

Connecting the pear push button to USB (not recommended)

Configuring NetAlarm

Now start up NetAlarm, go to settings, and enable external alarms. Select the COM port you connected it to, and you may also want to write another alarm type text here.

Enabling the use of COM port in NetAlarm