High Speed Data Aquisition on a PLC


Thread Starter

B Prigge

I am searching for a solution to a data collection problem. A customer wants to collect temperatures, pressures, rates, positions, etc. on an injection molding machine used for die casting. Some of the data is fast and some of it
is not. This particular application would be happy with 500 usec. sample intervals for the fast part. Once the data is in the PLC, uploading it to a useful form is yesterdays news.

Any suggestions would be greatly appreciated
PLC analog inputs are usually low-pass filtered on the front end to reject 50/60Hz common-mode noise. And, the PLC scan time can be 5+ msec, so
microsecond resolution is out of the picture.

The PLC is optimized for noise immunity for signals from widely distributed sources. This does not help for the confined spaces of an injection molding machine.

One possible work-around is to use an external A/D convertor and bring the data to the PLC via digital I/O in a parallel fashion. Will still be limited by PLC scan time.

Al Boake P.E.
ControlLogix has a new (No Manuals Yet, that new) card 1756-IF4FXOF2F. It is a hi-speed analog in/out card.

Input 400 uSecs (Floating Point)
Output 1 mSecs (Floating Point)

Probably worth looking into.

Best of luck
General purpose operating systems typically have a determinacy of milliseconds and above. Thus I believe that one can not use standard products for this high-speed data acquisition requirement unless the hardware buffers the data in a fifo and the driver is designed to empty that fifo on each read. Certainly, as Curt says, PLCs are not designed for this job

With a more direct connection between the computer and the IO converting the signals, this performance can be achieved and our software has been proven to be able to read, store and serve 100,000's analog signals per second. Recent benchmarks with a mixture of analog abd digital signals have shown performances of 2 million values read and stored per second.

Peter Clout
Vista Control Systems, Inc.
176 Central Park Square
Los Alamos, NM 87544-4031
(505) 662-2484
FAX (505) 662-3956
[email protected]
Six years ago I did an application using a Giddings & Lewis Motion Controller www.glcontrols.com to do a similar data acquisition task. All of the programming is done in ladder logic, Including the 'so called' Servo Task which IS the data acquisition.

The analog sensor input is treated as a servo input, thus is done on a deterministic constant sample time. The sample speeds we used at that
time was 1000 samples/second on each of four sensors. I believe the G&L processors today would allow us to run 250uSec or possibly faster.

In the application we were capturing analog information from four sensor heads, looking at the caps on baby food jars to determine if the safety lid was up or down. The speed was 40 jars/second.

The information was captured, analyzed on the fly and, if failed, the jar was 'kicked' of the conveyor. Because this is continuous operation, the data was placed it in a rotary que and contiguously analyzed.

The application works very well and is not difficult to set up.

If anybody has any questions, drop me a note.

David Kane
[email protected]

Gidding & Lewis Motion Controls

Michael Griffin

I would suggest that you are wasting your time considering a PLC for this type of data aquisition. The speed and accuracy required, and the amount of data involved make a PLC unsuitable.
You need some sort of computer, signal conditioning, a data aquisition board, and some suitable software. The size of a project to produce a truly useful custom system may be rather larger than you suspect.

Michael Griffin
London, Ont. Canada
Dear Mr Prigge,

There is an European PLC/Servo company called B&R ( "www.br-automation.com":http://www.br-automation.com ),
which is especially good at and famous in controlling plastics machines (injection, blow...). They have special modules (may not appear in their web catalog) dedicated to do such high speed analog input, at least I know they
have module which can take in 50Hz power signal and analysis the harmonics! If your customer is a plastics machine maker, they should know B&R.

Best Regards,
Mark Meng

John Paley--Graphic Pkg Corp

Even if you get your half millisecond captures, what are you gonna do with all that data??? The PLC memory will fill up--fast. You'll have to send it, chop chop, to some data storage device before that happens. If you're gonna have some storage device, anyhow, why don't you start with one that collects data?

Enrico Guasco

Please check SoftPLC product at www.SoftPLC.com I knoz for sure a System Integrator used a SoftPLC CPU (programmable in Ladder A-B style) with Hi
speed PCI card to collect analog datas and encoder pulses to determine humidity % in logs. Tat used to be a very Hi speed app.

Enrico Guasco

Tex.El. di Guasco Enrico
Borgata Ricca, 6
13822 - Mosso (Bi)

Tel. +39015702972
Fax. +390152548911
email. [email protected]
First of all, I wish to thank you for giving your input.

I am well aware of the shortcomings of the traditional PLC.

I am also aware of the daq equipment available in the isa/pc104 arena.

The data I want to capture would be an infrequent occurence but of a high speed nature. There are other things going on at the same time that we need to deal with that make the plc generraly a good choice.

I was hoping that there was a high speed capture card that fit in some plc that would collect x amout of data at x rate and start with a trigger.

Hi Brian,

What you are looking for is a transient recorder and you should search for these. They can be set up to convert continuously and then stop after a
delay from the trigger so that you end up with data from before and after the trigger. They will use local memory and come in an array of ADC bits and speed.


Michael Griffin

On February 8, 2002 05:29 pm, B Prigge wrote:
> The data I want to capture would be an infrequent occurence but of a high
> speed nature. There are other things going on at the same time that we
> need to deal with that make the plc generraly a good choice.
> I was hoping that there was a high speed capture card that fit in some
> plc that would collect x amout of data at x rate and start with a trigger.

The following doesn't really address your question, but I think it addresses your problem.
All I've seen for PLCs is straight analogue cards, while it seems that what you want is a data aquisition system in a card. Perhaps a data aquisition system that you can easily interface to a PLC will suit your needs. I suspect that your customer will eventually want to do some sort of analysis on the data being collected. In this case having something at the machine which can analyse the data as it is collected will be desirable.

Have a look at Sciemetric ( "www.sciemetric.com":http://www.sciemetric.com ). They build data aquisition and waveform analysis systems (hardware and software) for industrial (production line) use. They support a number of common industrial communications protocols for communicating with PLCs. They also have a number of pre-packaged solutions which they can sell as a complete off the shelf
You might also see if someone in the die casting equipment industry has an off the shelf system which can be integrated to the machine. I can imagine what it is your customer wants to achieve as an end result, and I would think it quite possible that someone has already solved this problem.

In either case, your customer would need you to integrate such a system to their equipment, as the operation of it would likely need to be closely co-ordinated with the function of the machine.

Michael Griffin
London, Ont. Canada
Plug in data acquisition boards can do this too, much less expensively than a transient recorder, usually, but they also require more integration work on your part. I can give you details, but not here since we maniufacture them...if you contact me directly I'd be happy to help

Rick Daniel
<[email protected]>
Yokogawa, I am not normally a big fan of, makes a electronic chart recorder that would fill your needs. Its called DAQ-Station. It has up to 30 universal data point inputs with meas periods as fast as 125ms for 8 points or a mix of fast and slower inputs. It will display the values locally, and store history and have connectivity to other systems.

Its best feature is an ethernet connection with a built in WEB server to take the data to what-ever where-ever you like, using standard PC hardware and software.

check it out at "http://www.yokogawa.com/tm/DX/":http://www.yokogawa.com/tm/DX/

Radislav Yanai


1. You must specify more precise the sensors you want to scan.

2. About 500 usec - it can be done with more specifications.

3. From my experience, you can use one of the C8051F00x family embedded microcontrollers. They are very fast and have a lot of embedded "toys" inside (a/d, d/a, pwm, spi, i2c .......). They works at 25 MIPS (even faster in new models). The suiatable firmware can be written in C-51. It can communicate with host via rs-232 channel at 115 kbaud (or more).

4. It works !!!!

5. Contact me on any question.

Best regards,
Radislav Yanai
Senior Hw/Fw/Sw engineer.

Roel Tijsmans

Siemens makes a card that can read inputs at 0.5ms
(see link below) called SM 335. Unfortunately, since the fastest interupt usuable is 1ms, I don't know how you can use this fast read in a usefull way and still use the PLC for "normal" things. if 1ms is fast enough however, you can have the card generate an interupt after the scan cycle is complete, and in the interupt program store data in a Buffer. Obviously you want the card to be in the same rack as the processor, and you should probably get one of the faster models CPU (CPU 315 or higher, like CPU318-2)

Roel Tijsmans
Spang Power Electronics
[email protected]


Driver Development Team

Here is some info that I received a while back that might be useful.

If you are having trouble getting data from some of your Injection Molding Machines, you will be excited to find that ASI has working, installed communication drivers for many of the Nissei machines! Send / receive data including:

Temperatures (set, actual, average) for all zones
Cycle Time and Fill Time
Maximum Screw Pressure
Plasticizing Time
Parts Counts (planned, rejected, remaining,...)
Event Data (timestamp and event description)
..and many, many more.

Almost every Nissei IMM is different, so what is available from you particular equipment depends on its configuration. Contact us to find out what parameters you will be able to set and read.

We specialize in communicating with factory equipment. If you are missing data from some of your equipment, 'reply' to this e-mail and just
ask - someone will get right back to you, and you may find that we already have a driver!

Thank you,

Driver Development Team
Advanced Systems Integration