Analog output 0-30VDC

[hillimonster]

With a PLC is it possible to get analog outputs of 0-30VDC @ 1.0 Amp max? It looks like the PLC analogs outputs go from +/- 10VDC. Does anyone know of a way to get a variable controlled analog from a PLC (possibly through another device) to get this kind of control.

Thanks

 

[Skogsgurra]

There are many devices that do that. A DC amplifier, for instance. But they usually are quite expensive, need a power supply and also (usually) have bipolar outputs. I think that you should look for a "programmable" power supply. 30 V and 1 A is kind of a standard specification. You get all you need in one packet. Connect to mains. Input your 0 - 10 V to the "programming" input and connect output to your load. Done!

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[itsmoked]

And review why you need such an output from a PLC..

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[xyzz]

And what resolution and responce time do you need?

 

[hillimonster]

Sorry for the long delay in response.

I am trying to get a variable output to a Valve device that is stepped from 1 Volt to 30VDC over time.
So my PLC Analog Output drives a device that can vary (from an analog signal) for 1 - 30VDC @2.5 Amps max Load. PLC outputs can't drive this kind of power or reach this voltage. The key is not setting the output of the power supply once but being able to electrically control it, without operator intervention.

Thanks

 

[ScottyUK]

Lambda's Vega range of modular swicthing power supplies have a variant which offers an output programmable by an external signal, either a pot or a 0-5V input. Their tech sales guys are really helpful. The configuration tool on their website ended up infuriating me so they configured one for me in next to no time.

Have a look at page 26 of

http://www.lambda-gb.com/files/Lambda Modular 2006.pdf

for a supply capable of swinging 0.5V - 32.5V at 8A output current. It's about halfway down the right side of the page - a W5 module. Probably a little overkill for your application but they may have a lower rated equivalent too.


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Sometimes I only open my mouth to swap feet...

 

[nbucska]

Would pulse width modulation be acceptable ? it would be simpler and more reliable.

Plesae read FAQ240-1032
My WEB: <

http://geocities.com/nbucska/>

 

[ScottyUK]

Something like a switchmode power supply with an analogue input as a reference? I am curious about why a home-brewed PWM would be more reliable than a commercial power supply unless the market for these things was big enough to support all the development costs of making it reliable or the selling price per piece was so high that the cost of engineering didn't matter. And even if the engineering cost didn't matter I'd still use a packaged part for the ease.


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Sometimes I only open my mouth to swap feet...

 

[TWControls]

I like the Phoenix Contact converters. They can can be used for a wide variety of signal conversion applications.

http://www.phoenixcon.com/products/interface/db/mcr2.asp

TW Controls -

http://www.twcontrols.com

 

[ScottyUK]

Yeah, they're nice units and useful in many applications but unfortunately not capable of delivering 30V @ 1A which was the original spec that the O/P gave.

 

[TWControls]

Your right Scotty

I missed that

TW Controls -

http://www.twcontrols.com

 

[Kiljoy]

We tried using a hydraforce proportional valve. They had an amplifier you could purchase as an accessory. Perhaps you should check with the valve vendor. We used a HYDRAFORCE P/N: 4000139. I beleieve it was designed to condition directly from a pressure transducer, but we just sent a signal from our PLC analog output.

 

[stilts]

Just joined, but you might try a place call Atkinson Electronics. It was an earlier place of employ. Their web site is

http://www.atkinsonelectronics.com

they make interface modules, and can make custom boards. Hope this helps.

 

[hillimonster]

I thought I would give an update to my solution, as it is now installed and running, for some time now. (delays by others, as usual!!!).

I bought a Instek GPS-S table top power supply that could supply 0-30VDC @ 3Amps. The key to it was that it had a slave mode, which could accept a Analog input of 0-10VDC, that would inversely give an output of 0-30VDC. The analog input was only required to be in the milliamp range, thus not over-loading the Allen-Bradley PLC analog output.

The power supply was in the $175 dollar range.

So the PLC Analog Output is stepped from 10Volts to 0 Volts, with approx. 2 seconds between steps. I can now see what nominal voltage the valve coil picks up at. Then once this is established I vary the PLC output from this nominal voltage back towards zero and record what nominal voltage the valve coil drops out at.

 

[danw2]

"The needle changes. . . ." ? ?
Huh? It's a digital supply. What needle?

I figured I'd bookmark the power supply with a control input on it that Billmonster mentioned. So I googled 'Instek GPS-S' and looked at the first hit.

There's mention of ISO-9001 and a host of approvals from various agencies, the typcial ya-da, ya-da. Then I see

"This is the Fact: The load on the needle changes
as it goes from above the skin (when you step on the foot switch)
to penetrating as you enter the skin and as you move around.

Instek responds faster to adjust current with consistent speed under different pressures as the needle moves against the skin through the
varying conditions of tattooing."

Oh. They're not talking about a meter needle on the p/s, they're talking about a tattoo needle!

You'll all be happy to know that

"Gone are the days of garage-tattoo artist manufacture.
No tattoo supplier is ISO-9001 Certified Manufacturer of Electronic Equipment."

The wonder of modern electronics.

http://www.unimaxsupply.com/equip/powersup/11ex19.1.htm

Dan