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PLC With Analog Input
« on: November 26, 2010, 12:30:50 PM »
If I had a PLC (DirectAutomation DL-05) with analog input capability of 0-10VDC, could I monitor that voltage in Mach using a brain?  My thought is to use this device as a THC and Monitor the voltage coming in on the PLC from the voltage divider.  Compare that voltage to a set voltage and trigger the THC up and down outputs as needed.  Could this be done?

There would also be some anti-dive logic involved.  Something like...If actual voltage exceeds set voltage by say 10%, suspend Z movement until voltage comes within range.  Could a brain do this as well?

TIA

Offline Hood

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Re: PLC With Analog Input
« Reply #1 on: November 26, 2010, 02:12:13 PM »
I use  brains with the current type analogue inputs for FRO and SRO pots but voltage type can also be used as its the same data that gets sent to Mach no matter which type of analogue input you use.

I compare the inputs and if below or higher than a set value it writes to the FRO and SRO override DROs, if between two values then it sets the DROs to 100% So its kind of like what you are asking so could probably be done although I dont really know anything about THC so cant say for sure.
Hood

Offline BR549

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Re: PLC With Analog Input
« Reply #2 on: November 26, 2010, 02:25:10 PM »
A brain can do it , BUT at 10 reads per sec it may be too slow to work at a usefull feedrate(;-).

Just depends, (;-) TP
Re: PLC With Analog Input
« Reply #3 on: November 26, 2010, 04:00:20 PM »
Would it be better to do the programming inside the PLC and have the PLC trigger the THC up and down?  I'm assuming the PLC has that programming capability.

The other hurdle is building a usable voltage divider.  I know the basic concept and can breadboard a simple two resistor device that works on a clean power supply, but not sure if that will work on a plasma power supply.  I suspect tip voltage is rather "noisy".  We have one power supply with an automation interface and one without.  Currently using a sound logic THC on that one, which works, but I need to add a PLC anyway for more inputs, so I'm trying to integrate the THC into that as well.
Re: PLC With Analog Input
« Reply #4 on: November 26, 2010, 04:04:01 PM »
For you guys that know brains inside and out, I had another brains questions.  Please take a look at this thread.

http://www.machsupport.com/forum/index.php/topic,16622.0.html

TIA
Re: PLC With Analog Input
« Reply #5 on: November 26, 2010, 04:44:43 PM »
Additionally, what would you guys recommend for a PLC.  I'm thinking the DL05 (Model D0-05DR)...

http://www.automationdirect.com/adc/Overview/Catalog/Programmable_Controllers/DirectLogic_Series_PLCs_%28Micro_to_Small,_Brick_-a-_Modular%29/DirectLogic_05_%28Micro_Brick_PLC%29/PLC_Units

And F0-04AD-2 add-on module for analog input. 

http://www.automationdirect.com/adc/Overview/Catalog/Programmable_Controllers/DirectLogic_Series_PLCs_%28Micro_to_Small,_Brick_-a-_Modular%29/DirectLogic_05_%28Micro_Brick_PLC%29/Analog_I-z-O

This my first time with PLC's, so I'm shooting in the dark as far as what I need.  Basically, I want the ability to input a few remote switches plus the analog input for a THC.  Near as I can tell, the above will do that, but if I'm headed down the wrong road, please set me straight.

Thanks

Offline Hood

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Re: PLC With Analog Input
« Reply #6 on: November 26, 2010, 05:25:38 PM »
I use the D0-06DR, its more expandable than the 05 so might be a better choice for the future. As said earlier I use the current type analogue inputs but I do have the voltage type and it works fine, so no problems there.

As for programming in the PLC then yes you should manage that, not sure the difference between the 05 and 06 but maybe better check up as I know there are a few things not available in the 05's programming capabilities compared to the 06.

Hood

Offline BR549

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Re: PLC With Analog Input
« Reply #7 on: November 26, 2010, 06:59:50 PM »
THC's are a very specific critter. I would suggest you get a dedicated THC.

(;-) TP
Re: PLC With Analog Input
« Reply #8 on: November 26, 2010, 07:16:43 PM »
Thanks guys.  I have a Sound Logic on the automation machine, which also works well on the manual machine.  I don't desperately need another THC but thought that I'd take the opportunity to try and find a better way.  I kind of like the idea of programming all of the THC code into the PLC...If it works.  PLC's are not terribly expensive, so it won't cost much to try.  I think the biggest hurdle is making a voltage divider than delivers a clean and relatively stable voltage.

Hood...Will the D0-06DR accept an analog input without using an add-on I/O module?

Offline Hood

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Re: PLC With Analog Input
« Reply #9 on: November 26, 2010, 07:20:37 PM »

Hood...Will the D0-06DR accept an analog input without using an add-on I/O module?

No.