×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

PLC analog comparators

PLC analog comparators

PLC analog comparators

(OP)
I need to incorporate voltage signals from thermocouples into a plc program, but the plc only accepts signals from 0.0V to 9.9V whereas the thermocouple voltages are in mV. Any ideas on how to convert these small voltages into valid signals?

RE: PLC analog comparators

Sanderscj,
    The input signal to the plc needs to be converted (obvious statement i know) the 0-9.9v sounds a bit unusual to me. I suggest if you have 24v dc available at the application, contact your local instrument and process control company ( look for one flogging thermocouples in thier ads. They can sell you a "2 wire hockey puck " unit which will give you 4- 20 ma . Run this through your plc input ( IF IT IS ISOLATED ) with a precision 500ohm resistor (ie < 1%) hooked in parellel across the input terminals.
    If the unit is not an isolated input talk to the instrument company they will have a suitable signal converter. The PLC manufacturer may have an input card to suit.
   What brand is the plc. You will not get a reading from the A/I terminals for a thermocouple. What temps are you measuring NEC have a chip thats good to about 50C.
Let us know how you go.
regards Don

RE: PLC analog comparators

Suggestion: Generically, a voltage amplifier is meant to amplify the voltage. Check manufacturer products over
http://www.thomasregister.com
for a possible thermocouple - plc finetuned set.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Resources

White Paper – Data Security and Know-How Protection
Our data is constantly exposed to the danger of being intercepted or stolen as it wends its way over global data networks. Data security measures and measures for protecting intellectual property should not, however, first be implemented when data is exchanged – companies must lay the foundation for these measures within their own organization. Download Now
White Paper – Collaboration in the PLM Context
The influence exerted by the Internet of Things (IoT) means that there is a steadily growing need for collaboration in industry. Partners from new industries and areas of application need to be integrated in cross-company business processes to ensure that the lifecycle of smart, connected products can be managed from end to end. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close