SiePortal

The integrated platform for your product selection, buying and support workflow - bringing together Industry Mall and Online Support.

Products & Services
- Menu temporary not available
- Menue temporary not available
- {{item.title}}
Support Support
{{(apiData.Support | filter:{'rank':1}:true)[0].title}} Support
- Menu temporary not available
- Menue temporary not available
- {{item.title}}
MySiePortal MySiePortal
{{(apiData.MySiePortal | filter:{'rank':1}:true)[0].title}} MySiePortal
- Menu temporary not available
- Menue temporary not available
- {{item.title}}
Cart ({{apiData.CartCount}})

Navigation

CTRL_PID Suddenly Gives Zero Setpoint

4/21/2019 5:09 PM	Rate (0)
khenchu Member Joined: 7/8/2016 Last visit: 8/6/2025 Posts: 9 Rating: (1)	Hi experts! I have twice encountered this problem in my plant's DCS. The CTRL_PID Block suddenly gives a zero setpoint in the SP parameter. Please check this screenshot. Facts: - At the time it occurred, there was no record in the PLC's diagnostic buffer of any kind of event. - The WinCC operator event log did not record anybody changing the setpoint from ??? to zero. - I replaced the PLC completely (PLC, power supply, rack, cp cards) three months ago. I believe I encountered this problem only since. And it only happened twice, roughly a month apart. - The first time I encountered this error on a different block, I moved the insert position from OB32(1s) to Main_Task(100ms). I didn't do it for the latest issue because I'm not really sure how that could've helped. I read about how stuxnet screws with the OBs but I really don't understand that. Does anybody have any idea about this mysterious problem (for me at least)? Thanks in advance! Attachment OKRdjlU.jpg (63 Downloads)
	Last edited by: Jen_Moderator at: 4/24/2019 6:50:12 AM Removed link and added file as an attachment.
Suggestion To thank Quote Answer

4/22/2019 9:18 PM	Rate (0)
Oreca Platinum Expert Joined: 3/14/2008 Last visit: 1/19/2026 Posts: 2233 Rating: (987)	Hello, Please upload a picture of the block /4 where SP_EXT is interconnected to.
	If I could help you, you can use the RATE button. Thank you. Prospact Netherlands...your PCS7 and PCS neo Expert Topic: PCS7 Complete Overview
Suggestion To thank Quote Answer

4/23/2019 3:35 AM	Rate (0)
JazTai Gold Member Joined: 9/9/2015 Last visit: 12/5/2025 Posts: 732 Rating: (285)	It seem like a programming issue instead of external factor.
	Please give me 5 stars Rating if my post is helpful for you. :) Thank you for Rating! Control System Manager Jaz Tai , Linde Gas Singapore PCS 7 Complete Overview PCS 7 Technical Documentation
Suggestion To thank Quote Answer

Share this page:

Share this page on...