Internet PLC Forum
General => Technical support => Topic started by: klundy on December 20, 2006, 04:18:12 PM
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I have the need to control 50 +/- 110vac Lighting Loads and would like to provide dimming capability.
I believe I can use the Digital Outputs of a T100MD or EXP4040 to turn On & Off Solid State Relays if I use 3-32v Input models.
But can I use the Digital Outputs to provide a PWM type of output using Special Bits / Clock Bits <and/or> some type of a clocked output to provide the dimming function?
If not, is there an expansion module or another solution that would provide a larger quantity of PWM outputs?
Thanks...
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PWM outputs are only suitable for controlling DC load. AC load are controlled by Triac OR SCR and not easily interface to a PLC.
Since you have so many AC 110V lights, you may want to look for a lighting control system that has RS232 interface (usually designed for a PC to control it). Then you can program the M-series PLC to control the lighting using communication command.
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There are analog controlled SCRs out there (e.g. http://www.power-io.com/products.htm). However you only have 2 analog out per T100MD so if you wanted to control all 50 lights independently you'd need a lot of PLCs. You could get external analog I/O modules, though, like those from ICP (http://www.icpdas-usa.com/i_7024.html) but you'd need a lot of those as well.
The suggestion above seems like your best bet.
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Using a standard output port will only give you a ON/OFF! What you could use is a Proportional SSR which uses an analogue input for 0-100% of power out. I use these often and work great!
Hope that helps!
Cheers,
Brett
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Might look at smarthome.com. They have x-10, and others powerline modem stuff that's fairly inexpensive and controllable with RS-232 and maybe other protocols.