Fire Station Automation: Relays, Contact Closure, etc.
Fire Station Automation: Relays, Contact Closure, etc.
(OP)
Hello,
I'm working on a fire station automation project, and I've got some questions about some of the more inexpensive PLC's out there (like an Omron Zen, or Click PLC):
Upon a momentary contact closure, I need to accomplish the following:
Switch a single balanced audio line to an amplifier (it sits in off position otherwise)
Provide contact closure for another relay that operates a bank of lights
Provide contact closure for a garage door opener
Provide contact closure for an audible tone generator
I am a novice with PLC's, and I'm having a tough time figuring out the input output capability, and relay capability.
For the audio problem above, I'd use a double pole, double throw relay normally, I'm wondering if the PLC can accomplish that on its own? It seems foolish to have to use a relay with a PLC since it can do that job itself.
The contact closures I imagine are no big deal? The tone generator has a common output, and requires contact closure to an input, the same goes for the garage door and light relay.
Any help is appreciated
I'm working on a fire station automation project, and I've got some questions about some of the more inexpensive PLC's out there (like an Omron Zen, or Click PLC):
Upon a momentary contact closure, I need to accomplish the following:
Switch a single balanced audio line to an amplifier (it sits in off position otherwise)
Provide contact closure for another relay that operates a bank of lights
Provide contact closure for a garage door opener
Provide contact closure for an audible tone generator
I am a novice with PLC's, and I'm having a tough time figuring out the input output capability, and relay capability.
For the audio problem above, I'd use a double pole, double throw relay normally, I'm wondering if the PLC can accomplish that on its own? It seems foolish to have to use a relay with a PLC since it can do that job itself.
The contact closures I imagine are no big deal? The tone generator has a common output, and requires contact closure to an input, the same goes for the garage door and light relay.
Any help is appreciated





RE: Fire Station Automation: Relays, Contact Closure, etc.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Fire Station Automation: Relays, Contact Closure, etc.
RE: Fire Station Automation: Relays, Contact Closure, etc.
Check this:
htt
Siemens and others make this same style device. They have better programming software too, but you have to pay for it I believe.
You have enough in the link above to completely design and test your job without buying anything. You can download the actual software which provides simulation.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Fire Station Automation: Relays, Contact Closure, etc.
Also, your insurance company may require the use of "Listed" PLCs or controllers. Many of the small economy model PLCs are not acceptable to the insurance underwriters for "Mission Critical" applications.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Fire Station Automation: Relays, Contact Closure, etc.
The radio contact closure lasts for one second, hopefully that's long enough.
I took the Teco Genie II software, and programmed it how I'd like to see it run -- do you have any fears over that unit?
I've got it setup to where if power failure occurs, the normally closed contact will allow the audio to go through for a dispatch.
I've seen these systems designed before using all mechanical timers and whatnot, I was hoping that a PLC/PLR would be a better solution for the four or five contact closures and timers that I'll need.
Any information is appreciated.
RE: Fire Station Automation: Relays, Contact Closure, etc.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Fire Station Automation: Relays, Contact Closure, etc.
Sounds great, I'll place an order and test out my program. I certainly like the function based programming over the logic ladder.
Second question,
Studies show that fading in audio alarms for firefighters is critical when they're asleep. A sudden alarm can cause bad health effects and startle these people while waking up for an emergency call.
I'm looking at using a Valcom 9927A paging tone generator:
h
The unit can make several different tones using contact closure.
I'd like to fade its audio output in, the only thing I can think of is something like a digital potentiometer. Does anyone have a better idea, or something simple that too can operate off of contact closure? Is this something a PLC or similar device can do? I'm at a loss on this one.
Thank you.
RE: Fire Station Automation: Relays, Contact Closure, etc.
For that smart relay you can get an expansion module that is transistor output. This gives you four outputs.
Google "digital volume control" and find a unit that takes pulses to step its volume up/down.
Another idea might be to build a resistor divider then use the smart relay's dry contacts to short the diver out in several steps.
You could also use an analog voltage volume control that takes in a voltage and changes the gain. Use a transistor-out to make a crude PWM voltage output to use for controlling the the aforementioned volume control.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Fire Station Automation: Relays, Contact Closure, etc.
RE: Fire Station Automation: Relays, Contact Closure, etc.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Fire Station Automation: Relays, Contact Closure, etc.
Thank you!
RE: Fire Station Automation: Relays, Contact Closure, etc.
Get real.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Fire Station Automation: Relays, Contact Closure, etc.
htt
I still like the IC idea better.
Ed
RE: Fire Station Automation: Relays, Contact Closure, etc.
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