Which PLC for this application

Hi,

I am new to PLC. Only experience is couple of lab experiments back in my undergrad engg.
We have a project where we have to computer control a process.
The inputs/outputs involve high voltage and current (upto 55Amps). Some temperature inputs too.
I am not yet sure about the number of inputs. Probably around 20 inputs and 20 outputs.

Right now, I am looking at Siements Win AC and AB Softlogix5800.
Good thing with the Siemens Win AC is the labview interface.
If I understand correctly the win AC is just software. I would
still need to get PLCs for actual control, right?

Can some one explain the softlogix5800? Like an overview.

Any other suggestions?
Thanks in advance.

I've been using WinAc. I'm using it with the MP-370Touch HMI from Siemens. It doesn't have any retentive memory so I have to transfer any values I want to save to an offline datablock and read it back in on startup. It is a software PLC, you won't need a PLC to do the control but you will need an interface to a remote rack (Profibus/Ethernet/???) and I/O cards on the rack.


I'm actually looking to move to an real PLC. This gives me more flexibility, options of changing HMI's without losing the control, and a much cheaper route as the WinCC flex promised for the application over a year ago still will not work on a MP370 with WinAC.

Logix 5800 is a soft PLC - ie, a program that runs under WinXP and performs PLC operations. You will have to have IO hardware and you will have to decide how you want to communicate with that hardware for Logix 5800 to control the IO points. You can choose device-net, control-net, profibus or Ethernet/IP. The first three will require a special card in your Win PC to interface to the bus. Ethernet can use your standard Ethernet NIC, but it lacks the advantage of the determinism given on the industrail control busses, but this may not be an issue depending on your application. Then on the oher end, you have to purchase an IO rack adaptor or Flex IO adapator. In my opinion, by the time you purchase softlogix 5800 and an IO card for our PC and the field IO comm adaptor, you could just have easily purchased a PLC processor card and moved control out of the computer (and all the WIN XP headaches). With all the add ons the soft PLC costs more. Either way you have to buy the IO. I've investigated soft PLCs several times over the years and time after time I end up going with a hardware solution - and you can call me paranoid, but I'm not yet ready to acquiesce safety concerns to a Win PC, in the end that is what has kept me from at least making the venture once.

With Logix5800 you still need RSLogix-5000 programming software.

Do not like software PLCs. If you have to turn the comuter off, or worse still if the hard drive or any other component fails, you are dead in the water.

Omron have a PLC on a PCI card. A separate power supply (24VDC) is required to the card. You can turn the computer off, remove the card and the PLC still keeps running.

You still need real world I/O.

Use a proper PLC. It is much easier.

Sounds like the job for a small PLC.
You need to drive the high current outputs via contactors.
A softPLC or SlotPLC will probably be budget overkill for such a small application. You would have to go via Profibus or DeviceNet to access the i/o.


If Labview is important for you, then check which PLCs interfaces the easiest with that software package.
Maybe someone here knows about Labview and PLCs.

Omron have a PLC on a PCI card. A separate power supply (24VDC) is required to the card. You can turn the computer off, remove the card and the PLC still keeps running.

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Siemens also has the SlotAC PCI card in 412 and 416 DP versions. But of course you then need Step7 to program them, which is pretty expensive for a small project if you don't have it lying around already. The SlotACs aren't exactly cheap either.

You will also need a full STEP7 Basic for WinAC.
If there must be a Siemens logo on the PLC, then I would look into an S7-300 + STEP7 lite, or S7-200 + MicroWin.
If AB is more tempting for 'backtoplc' then a MicroLogix + RSLogix500 Starter or a CompactLogix + RSLogix5000 Mini could be the answer.

I am wondering if the reference to Labview is indicative of a need for highspeed datalogging. If so, then a fast online connection (or indeed a SoftPLC) must be taken into account as well.

Hi guys, thanks for all the input. I wasn't able to check the replies, coz I had to move.
Right now, I am leaning towards micrologix+RSlogix combo as jesper suggested.
I have some more questions -
Do these PLCs come with built in relays? If yes, are they rail mountable?
Can external Rail mountable relays be used with these PLCs?
More detail the better.
Thanks again. This website is really useful!

backtoplc,

Sure, you can get a Micrologix with relay outputs or transistor outputs. It is an option to be picked when you order it. If you already have a copy of RSLogix, then a Micrologix PLC is a good choice. If your are paying for new software out of the old back pocket, then look at an Automation Direct DL-06 PLC, relay outputs, built-in LCD display option, cheap software, cheap hardware, order online, no hassles with no-brain salesmen.

I also think the DL-06, from AutomationDirect.com might be a good fit here. 20 inputs on board, 16 outputs + 8 output option card, + 4 channel thermocouple card would cost less then $500.00. Software is another $500.00 or the "brick" version (06' only), is about $160.00. You might get away with spending less then $800.00 on the total cost of PLC & software.

I would have to say that if getting this done cheap is a factor. which didnt sound like it when softlogix was mentioned. but if it was me. i wouldnt use it. ive learned that unless u using one processor. to control a large operation, or multiple processes. i like to keep it simple. like the micro 1000. if im not mistaken. there is a fixed I/O plc. that i have seen for less than a $100 on ebay.

but the temp controls will be your kicker. if i had the extra money go ahead and maybe try a slc 5/03 or 5/04. and get a analog input card and 2 of each of the 1746-IA16 and for contacts but not up to 55 amps. u could use a 1746-ow16 relay card and power it sounds like u will need to get u some 55amp contactors. and yes there are some that size that are dinrail mounted. if u need some part # on some let me know. im to lazy to get up and get book at the moment lol.
and some more details on what u are trying to monitor or control would help as well. what i just told u here may be useless if some factors with that software using is a problem. and as far as rslogix goes. there are trial downloads that would work if this is a one time job.


Simplifying is the key. Allen Bradley is creating to many features at one time lately if u ask me. I dont think all this communication **** is neccessary. ive never needed more than ethernet and DH+. but maybe im only exposed to small applications.

If you want to go small and cheap, Omron CPM1A is inexpensive, expandable and has analogue modules available. Also mounts on a DIN rail. I normally use transistor outputs and drive external relays. Much easier to replace in the middle of the night than PCB mounted relays. IT IS ALSO ONLINE PROGRAMMABLE!!! Many are not, including the Micrologix. I no longer buy PLC's that do not have an online programming facility. Pain in the "A" quite frankly. Old fashioned in this day and age.

The other reason I would suggest Omron is the software. CX-One is now out and is very inexpensive. It will program all Omron PLC's from the old C200H onwards. It also has networking, motion, NC, temperature, Device Net Configurator, position, process tool, simulator, NT screen, protocol, switch box etc built in. Brilliant package and it is only V1. The whole package for much less than most brands. It is also on special at the moment. Upgrade prices are very reasonable. You also get FB and STL, if you require them. B****y good buy.

Lancie, yes it will be our first PLC software purchase.
Thanks for mentioning the DL 06 everyone.
Cost is always a factor. cheaper the better. If its less expensive and works, the boss will be very happy.
I got a couple of questions regarding the DL 06 - can it handle 30A and voltages upto 3kv?

Here's more info abt the application -
Our job is to automate/control a Q machine. Its a machine used to study waves and ionized plasmas. Pure physics stuff. To get the Q machine started and going, presently we need to switch on/off several buttons and also increase/decrease current until certain temperature is reached.
I still need to get more details, but thats all i know for now. Its high voltage and high current.

BoBb, thanks for mentioning the omron. Is it suitable for the above mentioned current and voltage?
Thanks again guys.

BoBb, thanks for mentioning the omron. Is it suitable for the above mentioned current and voltage?

Click to expand...

Depends what you mean. If you are refering to switching 30A at 3kV, you will need to switch a contactor/vacuum contactor capable of handling that voltage and current.

Please explain further. I do not know of any PLC that can switch those figures directly.

Many PLCs have up to 2.5kV surge protection on the inputs.

Backtopic,

You can download the DL-06 manual Here:
http://web3.automationdirect.com/static/manuals/d006userm/d006userm.html

I dont know of any PLC that can directly switch 3kv @ 30 amps, or take a 3kv punch to an input. The PLC is a Programmable LOGIC Controller. That means that it is designed to handle the logic needed to operate the machine (sequence, timing etc..). You will need additional devices, reguardless of brand PLC, to handel your power for the plasma generator.