Using digital I/O ports to switch 240vac?

hodeyp

Hi,

I am looking to use the digital I/O ports to switch a 240vac circuit (rated 120 watts). I've never done this before and would appreciate some suggestions on how to acheive this.

any ideas?

Thanks

Phil

vining

I think you mean "use a relay port" not i/o. You then need another relay that uses a 12vdc control coil that is capable of hanlding your loads voltage and amperage. Look at "RIB Relays" for this. Use the NI's relay ouput to control the load relay tapping 12vdc off the amx power supply through the NI's relay to provide the coil voltage to pull in the load relay.

TurnipTruck

hodeyp wrote:

I am looking to use the digital I/O ports to switch a 240vac circuit (rated 120 watts).

If you must use the IO ports for load control, I would suggest the use of an electronic-type relay, not a coil, as the current needed to activate it will be much less. The current dissapation of the IO ports on Netlinx masters is rated at 200 mA.

Electronic relays are sometimes referred to as SSRs (solid state relays) or "Hockey Pucks." They are commonly made by Omron and Crydom and avaiable through Grainger and the like. There are models that can do 240 volt switching. Get one that has a low-voltage DC control side.

The positive of the control side of the relay would go to the +12VDC positive of the control system power, the negative would go to the desired IO port. The load side of the relay will break your 240 VAC. If the 240VAC is from a split-phase power system (two hots) you should use two relays and break both phases. I do not beleive that I have ever seen double-pole electronic relays.

dchristo

TurnipTruck wrote:

I do not beleive that I have ever seen double-pole electronic relays.

Not inexpensive, but Allen-Bradley makes 1, 2, or 3 phase solid state contactors (156 series). 5-24vdc control, 24-600V, 20A load side.

--D

vining

TurnipTruck wrote:

I would suggest the use of an electronic-type relay, not a coil, as the current needed to activate it will be much less.

The coil on the RIB relays http://www.functionaldevices.com/ChartPilot.html is only 14ma @ 12vdc and if you can't spare that amount of current from the power supply then your power supply is extremely under sized.

Colin

240vac

If you are in Australia or New Zealand, AMX Australia have a couple of products to suit your application they being the
AXB-RC8DIN which sits natively on AxLink or the AVT-RC8DIN which is controlled from Opto-isloated ports

hodeyp

thanks everybody. i'll take a look at the options you have given me!