Smoke and Fire Sensor

[sid80555]

I have been looking online for a smoke and a fire sensor which can be interfaced with the FMD88-10 plc. It would be of great help if anyone of you could let me know which fire and smoke sensor is compatible with the inputs of this PLC. Also how can i interface this sensor with the PLC
Kind Regards,

[support]

It depends on whether what you need is just a smoke and fire detector (ON/OFF) or an analog sensor that can give you amount of smoke it receives.

If it is just a detector that gives you ON/OFF signal then preferably  look for one that output a voltage-free dry contact which can be interfaced to any of our PLC digital input.

If it is an analog sensor then look for one that can output 0-5V, 0-10V or 4-20mA. All of them can be interfaced with the PLC's analog inputs either directly or coupled using a one or two resistors to convert the sensor's voltage output to 0-5V that are compatible with most of our Super PLCs (F1616-BA is currently the only one that interface directly to 0-10V sensors).

[sid80555]

I need to interface a PIR sensor to the FMD88-10.The output is a normally closed relay.Would i need to interface this to the digital or analog input in the PLC?Also do i use the TESTBIT function to read the output of the Sensor? If not how should i read the sensor outputs?

[support]

If it is a relay you simply connect one contact of the relay to the digital input and the other contact to 0V of the PLC's power supply. When the PIR sensor triggers the digital input will be turned ON.

The input is immediately available on the ladder logic. Within TBASIC you can use TESTBIT or TESTIO (labelname) to test its logic status and make decision in your program.

[sid80555]

When i connect the PLC to the laptop and transfer the program it says check error with PLC id. And Tri-logic gets hung.Also it restarts my computer sometimes. I connected it to the digital input and used the Testbit instruction(X=(testbit[1],2)).However it does not show me any change in the output of the sensor.When i use a mutlimeter to check the output of the Sensor it seems to be working fine (with 10 ohm output when it doesnt detect anything and Overload when the PIR detects and object).

[support]

How is the PLC connected to the laptop? What kind of interface (RS232 or Ethernet)? Is this the first time you are programming the FMD88-10 PLC? Note that if you are programming the PLC via RS232 you must run the TLServer simultaneoulsy. The instructions is in the i-TRiLOGI Programmer's Reference manual.

I thought you said it is a "relay" contact on the PIR sensor in the earlier post? What do you mean by 10 ohm when not detected? If it is pure relay contact it should be infinite resistance (open circuit) when PIR sensor not detecting anything and a 0 resistance when detected (or the other way round if it is a normally closed output). What do you mean by "overload" on a multi-meter? It doesn't quite make sense.

If the PIR sensor is connected to the PLC input via relay, you should be able to see whether the PLC input green LED is light up or not when the PIR sensor sensed something vs not sensing. You can measure the voltage on the PLC's digital input in the two states (sensed and not sensed) and check against the PLC's specifications.

[sid80555]

The digital input shows that it has detected something by the light glowing.However the voltage is randomly fluctuating(few mV) when the PIR detects and does not detect an object.I guess a change of few mV can just be considered some kind of noise?

[support]

Can you find out what the PIR sensor output is supposed to be when an object is detected vs when nothing is detected? You need the technical spec in order to properly interface to the PLC.

[sid80555]

This is the PIR i was looking to interface.This is what i got along with the PIR as well.Hope this helps.Thanks

[support]

Try connecting the terminal #3 to 0V of the PLC's power supply, and #4 to any of the PLC's digital input.

This is normally closed. Meaning the input will be ON (green LED light up) when nothing is sensed. When it sense something the input should be open circuited and therefor the green LED should go off.

[sid80555]

I have done this.But when the PIR senses something and when the red light in the PIR is about to turn off, the digital input light in the plc turns on for a fraction of a second.

[sid80555]

It is working fine now But when i use tri logic to store the values of the digital input(in X register) it runs for a while and then gives me an error message saying error in node1 and tri logic gets hung.

[support]

What do you mean to store the values of the digital input in X-register? You only one 1 single bit input in this case. You can use it in ladder program or if in TBASIC you can use the TESTIO function to check the status of the input. Do not put into an endless WHILE loop to check for the digital input status. That may be the reason your program hang. The best way is to use the digital input status on a ladder portion of the program to act on it. If you want to use TBASIC then run a non-differentiated custom function to check the input every scan of the ladder program until the status changed.