You are not registered yet. Please click here to register!


 
 
plc storereviewsdownloads
This board is for PLC Related Q&A ONLY. Please DON'T use it for advertising, etc.
 
Try our online PLC Simulator- FREE.  Click here now to try it.

---------->>>>>Get FREE PLC Programming Tips

New Here? Please read this important info!!!


Go Back   PLCS.net - Interactive Q & A > PLCS.net - Interactive Q & A > LIVE PLC Questions And Answers

PLC training tools sale

Reply
 
Thread Tools Display Modes
Old February 23rd, 2018, 08:39 AM   #1
merlin00724
Member
United States

merlin00724 is offline
 
Join Date: Oct 2007
Location: cincy, OH
Posts: 33
flex IE8 raw issue

I am having some issues with a 1794-IE8 flex module on a controllogix plc. this is measuring the weight of a tank on load cells. the scaling seems to be right with the module set for 4-20mA and the raw min/max is 0-30840, but with a measured 3.8mA from the transmitter I am getting a raw value of 40. which is showing the tank as not empty when it really is. we have about 12 tanks set up like this and they all behave the same, and have since being commissioned new. so I am not really going down the road of thinking I have an isolated hardware issue. if I simulate 3.7mA to the module then I finally get a 0 raw value.

any advice on how to tighten this up so that at 4 or 3.9mA I can get a 0 raw?
  Reply With Quote
Old February 23rd, 2018, 11:16 AM   #2
Mickey
Lifetime Supporting Member
United States

Mickey is offline
 
Mickey's Avatar
 
Join Date: May 2003
Location: Palmdale,Ca
Posts: 10,145
That is 0.1 of 1 %, pretty small error. What is the engineering units (span)?

Can the 4-20ma transmitter be adjusted(calibrated)? If not you could do this in the PLC.

If it is just a high zero issue you could program a zero cut-off. Any thing below value xxx will show zero. Common method as most transmitters drift a little.
__________________
Mickey

If you want happiness for an hour-take a nap. If you want happiness for a day-go fishing. If you want happiness for a month-getmarried. If you want happiness for a year-inherit a fortune. If you want happiness for a lifetime-help someone else.
----- Chinese Proverb
  Reply With Quote
Old February 23rd, 2018, 01:01 PM   #3
merlin00724
Member
United States

merlin00724 is offline
 
Join Date: Oct 2007
Location: cincy, OH
Posts: 33
Thanks for the input. A cut-off might be the way to go
  Reply With Quote
Reply
Jump to Live PLC Question and Answer Forum

Bookmarks


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Topics
Thread Thread Starter Forum Replies Last Post
Factory Talk SE Trending issue snordvikqplas LIVE PLC Questions And Answers 0 February 24th, 2015 09:15 AM
Rockwell Flex I/O issue JohnCalderwood LIVE PLC Questions And Answers 5 July 25th, 2014 12:07 PM
Allen Bradley Power Flex 70 VFD fault 85 issue david n pittsley sr. LIVE PLC Questions And Answers 1 December 9th, 2011 10:38 AM
how to Open Wincc Flex 2005 sp1 HF7 in WinCC flex 2008 compact/standard/advance xohaibalam LIVE PLC Questions And Answers 7 October 13th, 2011 09:38 AM
Remote I/O Flex I/O Quick Change Tooling Fixture TamHoNutech LIVE PLC Questions And Answers 1 September 29th, 2005 06:46 PM


All times are GMT -5. The time now is 05:33 PM.


.