Selecting a used PLC for a "newbie" to practice with?

[TheEquineFencer]

Hopefully I'll have a legitimate copy of RS500 to program micrologix and SL500 series PLCs. A guy in another group is going to mail me his old version of it. It seems they upgraded to new version and told him he could have the old laptops to do as he pleased. I've called my local AB distributor and have yet to get a reply back. I left them a voicemail about want to buy the latest and greatest version. I did talk with AB tech support and found out Windows 10 will not be supported until June of this year.

What I plan to attempt to do is buy a used PLC or complete rack/racks to practice programming. I have a few projects in mind. On one of them I'm sure I'll need an analog input or two. I want to monitor a bank of batteries that are charged by solar panels. I want to use it to disconnect the battery bank when the charge level reaches a set LOW VOLTAGE cutoff point and reconnect when it rises above that point. I'll also need some digital relay type contacts to control the outputs. The Max input voltages usually never rise above 32VDC, but I'm sure I need a little more "cushion" for safety. The outputs I can use them to control everything else by letting them energise some relays that will actually be carrying the loads.

The other little project I want to try is to build a track torch that will start/stop at the end of a cut and then go back to the original start position. I guess I just need a PLC that will be relay outputs. I guess the inputs can be 120/240VAC. I've not decided if I want to use micro switches or Prox sensors for the inputs yet.

I have a Hossfeld bender I'm converting to Hydraulics, I may just run it without a PLC for what I want to do for safety reasons and just use micro switches for when it reaches the end of the travel to stop.

I'm open to suggestions. I have taken a couple of classes at the local CC on PLCs, we used SLC503 series in that class. I just want to get my feet wet again and get the basics down. I'm above average when it comes to wiring and figuring out how to get things to work. I'd like to be able to get a better job doing a little PLC work as most jobs around here are looking for that.

Thanks in advance for any help.

 

[jstolaruk]

I believe the best bang for the buck in PLCs that are programmed with RS500 is the ML1400, specifically the 1766-L32BXBA. It features 20 DC inputs (8 of them fast), 12 outputs (6 relay, 3 DC fast, 3DC normal), 4 analog inputs, 2 analog outputs, 1 ethernet port, 2 serial ports, etc. The 1766-L32AWAA is the AC input version.

You'll have to voltage limit those analog inputs.

My last I bought on ebay for $300 for my test bench. Very hard to beat. I recommend this for most smaller machines I do if the customer can't afford the newer Compactlogix bricks.

http://literature.rockwellautomation.com/idc/groups/literature/documents/in/1766-in001_-en-p.pdf

 

[Bering C Sparky]

Hello,

I don't think you will want to take your solar charger voltage directly to your analog inputs, you will need to use an intermediate device that you can input say 0-50 vdc into and it will output 0-10 volts or 4-20 mA or what ever you like.

I have worked with another individual on just such a project.
He installs solar panels for lighting centers for orphans in Africa.
Look at this thread and go to post #5 then look at his link that says "Sensor" you can see such a device I am talking about here.

http://www.plctalk.net/qanda/showthread.php?t=96827

BCS

 

[TheEquineFencer]

Hello,

I don't think you will want to take your solar charger voltage directly to your analog inputs, you will need to use an intermediate device that you can input say 0-50 vdc into and it will output 0-10 volts or 4-20 mA or what ever you like.

I have worked with another individual on just such a project.
He installs solar panels for lighting centers for orphans in Africa.
Look at this thread and go to post #5 then look at his link that says "Sensor" you can see such a device I am talking about here.

http://www.plctalk.net/qanda/showthread.php?t=96827

BCS

I agree, I'll have to build a voltage convertor. A 4-20 mA signal might be better, I know that's used a lot with PLCs. I'll have to do some more looking later, I've got to get to bed, 5 am is going to come early.

 

[Bering C Sparky]

I agree, I'll have to build a voltage convertor. A 4-20 mA signal might be better, I know that's used a lot with PLCs. I'll have to do some more looking later.

If you are going to go 4-20 mA just be aware that some of the Micrologix line of plc do come with analog inputs but they are NOT current inputs, they ARE voltage inputs.

If you are going to use Micrologix and also use 4-20 mA then you would also need to purchase an additional Analog input module.

Just FYI.

BCS

 

[V0N_hydro]

or get yourself a 250 ohm resistor and convert 4-20 mA to 1-5 V just like the PLC probably does anyway

 

[TheEquineFencer]

I heard from my PLC buddy in Calf. My PLC programs are on the way! I also got a call from a "headhunter" Friday, they saw my resume on Careerbuilder, they are interested, especially if I'm able to do some PLC work. Things are looking up for a change. Work is slow at the regular job, we go back to work for at least a day tomorrow.