Analog input/output ideas for SLC 500

[johnnysparks24]

Hello, I'm looking for some ideas on choosing some simple analog input and output devices. I have a analog input card (1746-NI4)for either -20mA to +20mA or -10 to +10vdc. Also I'm going to get an output card that will be choosen with help from your suggestions. What I'm looking for is some devices that will help me learn analog programming, I need a simple yet effective input device and again a effective output device that I can control with whatever output card I chose. If I get some feedback I'll gather the tools I need and from there start learning the process of analog. Thanks again for your help.

John

 

[vettedrivr]

As long as you're just experimenting anything will work. You can use a pressure transducer (0-10vdc) to feed the analog input card. Use a small DC motor drive like Dart/Boston/Fincor and run the analog output card to the drives 0-10vdc speed pot signal, usually P2 for (+) and P3 for (-). You can hook a 110v light bulb to the drive amature connections (arm + & arm -) if you don't have a motor. Connect the pressure transducer to an air source that you can vary the pressure on. When you get the logic written you can vary the brightness of the light (or the speed of the motor) by varying the air pressure. Substitute the pressure transducer for a level/temperature transducer or Linear Displacement transducer (LDT), replace the motor drive with an electronic pressure regulator/valve position controller/temperature controller and experiment away.

 

[johnnysparks24]

We have lots of dart drives and dc motors at work I think they are 0-90vdc, I never thought of using them. The pressure transducer is somthing I know we don't have, I thought of a variable dc power supply???? Any other input choices? whats the going rate for a transducer?
Thanks for your help.

 

[vettedrivr]

A variable power supply will work fine. The dart drive rating of 90vdc is the output to the motor. Normally the speed pot is just a voltage divider producing a 0-10vdc is the speed signal, P1 is the +10vdc supply from the drive, P3 is the ground side of the speed pot, P2 is the variable voltage signal. Eliminate the speed pot and connect your analog output to P2 (+) and P3 (-) to control the drive speed. A pressure transducer will run between $150 and $500.
Configuring everything for 0-10vdc/0-5vdc/1-5vdc makes troubleshooting simpler for those not used to using 4-20mA/0-20mA current loops.

 

[yfcarer]

Hi, friend.

When I began my work as an automation engineer, I used a kind of device called as "process simulator". I do not remember the brand of it but I remember it is very useful to simulate the process. It can give out a signal as AI and receive two AO as two valves. You can adjust the response of the process and for sure, it helped me a lot.

 

[Tom Jenkins]

FOr learning purposes I suggest making a 4-20 mA simulator. This can be as simple as a potentiometer in series with a resistor connected to the 24 VDC power on your PLC. That will let you adjust analog signals.

Start out with scaling the signal to engineering units representing some mythical sensor like pressure. Try simple High and Low alarms, which will let you get experience with comparisons and time delays. Move on to making the analog output, which you can measure with a standard multi-meter, proportional to the input signal. That will give you some experience with math.

 

[johnnysparks24]

parts list

Hello Tom or anyone,

What value of potentiometer and series resistor would you recomend. The card is 1747-NI4.

 

[Jimmie_Ohio]

Hi, friend.

When I began my work as an automation engineer, I used a kind of device called as "process simulator". I do not remember the brand of it but I remember it is very useful to simulate the process. It can give out a signal as AI and receive two AO as two valves. You can adjust the response of the process and for sure, it helped me a lot.

This is the best way to learn how analog I/O works...

Get a "process simulator" which (to me) means a device to both generate 4-20 mA and measure 4-20 mA. Then hook this into your analog I/O. Then just "play"

Try entering numbers into registers with simple move instructions to the output. See what "real world" current you get out. Likewise, dial current values from the process generator into the analog inputs and see what kind of numerical values you get. Make some calculations on paper for intermediate values, then see what you get when you dial them in.

To me, this is the best way to get comfortable with analog I/O. In fact, I will not hook up any analog device to my PLC until I have checked the operation with a "process generator" to verify what it puts out and how it behaves when I crank in 4-20mA.

 

[johnnysparks24]

Is their a particular process simulator or generator that you recomend or do you have a part number. Is this somthing you built, or do you know where I could get one.

Thanks John

 

[Mickey]

Click on millamps,Loop and Dc Calibrators under produts and calibration and test equipment

http://www.transcat.com/default.asp

 

[Marc]

Here is what we use at work, we have several of them and they take a 9 volt battery and/or power supply. They both source and measure current and voltage.

http://www.extech.com/instrument/products/400_450/412355.html

Marc

 

[johnnysparks24]

Parts list

Hello,

I plan on heading to our local electronic parts supply house this weekend, I was just wondering if someone could possibly tell a recommended value for a potentiometer and resistor to use for Tom's reply.

The equipment I have is my own I try to minimize costly mistakes which is why I come to you guys for ideas and help.

Thanks greatly

PS. I have yet to purchase a anolog output card, as I'm not sure which one would be the best for a training sinario. I don't know if I should go current out or voltage out????

Thanks John

 

[johnnysparks24]

Any help at all??

Not interested at all???



John

 

[Tom Jenkins]

Your best bet is a combo current input/output card - less expensive than two separate cards. I suggest current because first of all 4-20 mA is the most common analog signal in North America, it is easy to simulate, and because it will give you experience in dealing with that 20% offset.

 

[castlerock]

Hello Tom or anyone,

What value of potentiometer and series resistor would you recomend. The card is 1747-NI4.

you'll need a 1200 ohm resistor and a 4800 ohm pot using a 24 volt power supply. i'm not sure about a 4800 ohm pot being available though. you may have to settle for a 5k pot but another resistor in parallel will give you the 4800 ohms you'll need. my electronics are pretty rusty and i'm away from my books right now so i can't tell you the exact value of resistor you'll need to parallel with the pot. ( but i'm sure someone can. )

also, if you want a real device to play with on the cheap, check out the pressure transmitters at Jumo.

good luck

P.S. - obviously i used ohms law to figure resistance values, but it would be nice if the smarter people hsere would check my math. =]