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

Monitor PLC Remotely

Monitor PLC Remotely

Monitor PLC Remotely

I have a compressor station that is equipped with a "Station PLC" that runs everything. There is also a remote field office that monitors several of the station parameters via SCADA. In other words, an operator can be at the field office and look at a screen that displays the current compressor discharge pressure. At the station, there is a pressure transmitter located on the discharge piping. It sends it's signal to the Station PLC. The Station PLC sends the signal to the field office via SCADA. The field can only monitor, nothing else.

So...on the P&ID, the PT is a bubble on the piping, with a line going to a square box with a diamond/single horizontal line (indicating PLC at station panel). To indicate that this signal is also available for monitoring at the field office, do I merely make the single horizontal line in the diamond a double line?.....double line with text "Field Office"?.....or another symbol altogether?....and what type line to indicate the link?

I am not an instrument engineer.

Thanks all.

RE: Monitor PLC Remotely

Based on my experience, I would stick pretty closely to ISA symbology. Drop the horizontal line in the diamond/square box to indicate it is field mounted. Run a software signal link from that to another square box/triangle with a line through it for the office location, if that's the primary location.

You could put Field Office next to the symbol for the SCADA in the office. You may want to put SCADA text next to it to eliminate confusion in the future. However, your loop sheets and plan drawings should clear up the text issues on the P&ID's. I'm not a fan of cluttering up P&ID's for stuff like that. It isn't wrong just unnecessary. Double lines are for auxiliary locations normally accessible to an operator.

If your SCADA is PC based, the correct symbol is a hexagon, with a horizontal line through it and no square surrounding it.

Pamela K. Quillin, P.E.
Quillin Engineering, LLC

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


White Paper - How ESI is Helping Move New Medical Device Product to Market Quicker & More Cost Effic
Early Supplier Involvement has long been a strategy employed by manufacturers to produce innovative products. Now, it almost seems like a necessity. Because decisions made in the design phase can positively affect product quality and costs, this can help add value to OEM bottom lines. This white paper will discuss many facets of ESI, including why it’s so valuable today, what challenges limit the benefits of ESI, how cost is impacted, and more. Download Now
White Paper - Moving to a Driverless Future
This white paper describes what we see as the best practices to support a sustainable engineering process for autonomous vehicle design. It exposes how to use simulation and testing in common frameworks to enable design exploration, verification and validation for the development of autonomous cars at a system, software and full-vehicle level to drive a mature product development process for automated driving. Download Now
Research Report - How Engineers are Using Remote Access
Remote access enables engineers to work from anywhere provided they have an internet connection. We surveyed our audience of engineers, designers and product managers to learn how they use remote access within their organizations. We wanted to know which industries have adopted remote access, which software they are using, and what features matter most. 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