120vac inputs
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I really like the Click for basic stuff. 120v inputs are very common for plc's. If someone doesn't make one with 120v inputs they need to pull their head out....
http://www.automationdirect.com/adc...lers/CLICK_Series_PLCs_(Stackable_Micro_Brick)
The software is super easy to use and free to download.
http://www.automationdirect.com/adc...lers/CLICK_Series_PLCs_(Stackable_Micro_Brick)
The software is super easy to use and free to download.
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5,771 Posts
The A-B Micro 800 Series PLCs have versions with 120V inputs, and the programming software is free to download off of the internet.
http://ab.rockwellautomation.com/Programmable-Controllers/Micro830#/tab5
It's not "special" for companies that market primarily to the North American market, then secondarily to the rest of the word. But for companies that make their products primarily for the rest of the world, then secondarily for North America, 120V inputs are expensive to develop and maintain based on what they consider to be a relatively low volume. Nobody outside of NA uses 120V for controls. People in IEC countries used to use 230V for controls, but recent changes in safety requirements have them all using 24VDC now for everything they can, so that includes PLCs.
http://ab.rockwellautomation.com/Programmable-Controllers/Micro830#/tab5
It's not "special" for companies that market primarily to the North American market, then secondarily to the rest of the word. But for companies that make their products primarily for the rest of the world, then secondarily for North America, 120V inputs are expensive to develop and maintain based on what they consider to be a relatively low volume. Nobody outside of NA uses 120V for controls. People in IEC countries used to use 230V for controls, but recent changes in safety requirements have them all using 24VDC now for everything they can, so that includes PLCs.
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5,771 Posts
No, it means there is an actual tiny relay inside the I/O card wired to the terminals, as opposed to a solid state output, transistor (for DC only outputs) or triac (for AC outputs). The problem with using solid state outputs is that they can have "leakage" that can cause issues, and if they are switching anything inductive, like a coil, their current rating is very very low because of inrush and inductive kickback. Relays provide you with a real air gap isolation in the circuit and usually a little more current capacity. But solid state outputs can be much higher density, much higher speed and they don't wear out if you have a high duty cycle.
A PLC "relay output" means the PLC's output point is a set of dry contacts (usually N.O. only). You would have to check the spec's on the I/O module to find out the rating, but usually it can handle 120VAC and maybe 2-5 amps.
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