CompactLogix – 5380: Why Are My 5069-IF8 Analog Inputs Updating Slowly? (Q&A)

One of our community members recently asked what would cause his 5380 analog inputs updating so slow?

His application required that each 5380 analog inputs updated every 10ms, but what he was seeing in the field was a much slower.

When working with analog inputs and Logix PACs, two settings will effect the update rate:

1) RPI (Requested Packet Interval)

RPI is how often you’d like the controller to read the values from the Input modules.

It is named “Requested” because it’s a target the controller uses, but guaranteed update rate.

Because of this, Rockwell suggestions setting this rate at twice as fast as you actually need the data.

So in our Member’s case, to insure his Analog Inputs update no slower than 10ms, he should set it to a 5ms RPI.

2) Filters

Many PLC Input Modules have a built-in feature which allows the user to “Filter” the input signals.

A side effect of these filters is that the input which is being filtered updates at a slower rate.

In the case of the 5069-IF, the manual has a table which helps users understand how the RPI and Notch filter interact:

• 5069-um005_-en-p.pdf

Table Eleven in the above manual shows the Notch Rate filter on the left, and then the suggested RPI on the right.

In this member’s case, I pointed out that with the 5000 Hz Notch Filter for all channels, the table recommends a 4ms RPI for faster updates.

In the field he actually used slightly faster settings, and was very happy with updates coming in reliably at under 4ms.

If you have a related question or comment please post it as a reply to this post, or if you have a different question for our community, please post it as a new topic.

Until next time, Peace ✌️ 

If you enjoy this episode please give it a Like, and consider Sharing as this is the best way for us to find new guests to come on the show.

Shawn M Tierney
Technology Enthusiast & Content Creator

Eliminate commercials and gain access to my weekly full length hands-on, news, and Q&A sessions by becoming a member at The Automation Blog or on YouTube. You'll also find all of my affordable PLC, HMI, and SCADA courses at TheAutomationSchool.com.

• Author
• Recent Posts

Shawn Tierney

I'm a lifelong Technology Enthusiast who started programing in the early 80's on the new Apple II and VIC-20 personal computers. After earning a degree in Electronics, I worked as a Certified Automation Specialist for 25 years before leaving to focus on teaching at The Automation School, as well as publishing industry news and product how-to’s at The Automation Blog.

Latest posts by Shawn Tierney (see all)

• 2024 Podcast Audience Polls: Vote before January 8th! - December 18, 2024
• All 2024 Audience Choice Polls: Vote before December 31st! - December 18, 2024
• Position Guided Vision (P232) - December 18, 2024