Audit

Do you have an up to date list of all PLC model types, part availability, program copies and details for your company?

The first step to take is to perform a PLC audit. Open every electrical panel, and write down the PLC brand, model, and other pertinent information. Then go the next two steps. Analyze the audit information and risk, then act on that analysis. To help you out, I want to share with you our company PLC audit form.

Collected Information	Recommended Action
Machine or Area Name	Ex: warehouse conveyor, pump station 3,Strapper 2, Line 7, Traffic signal west main, etc.
PLC Program Name	Ex: 1789GAA1, P3, Strap2, 5872443, WestMainTL, etc.
Network Node Address	No two addresses will be the same. Ex: 2, 3, 17, 21
Network Name	Common to be same as Program name, but not mandatory.
PLC Brand	Ex: Allen Bradley, Siemens, Schneider, Mitsubishi, DirectSoft, Omron
PLC Model Number	Ex: PLC-5/25, SLC-504, SIMATIC S5, MELSEC FX1N, DL 405
Is Spare Available	Yes on shelf, or only in less critical machines or no
Date Program Last Backed Up	Make program backups part of your semiannual PM program
Discriptored Copy of program available	Without discriptored copy of program, troubleshooting and downtime are greatly increased.
Does PLC have EEPROM	Or other method of storing backup program in a chip on PLC
Last date Program Changed	Remember to log when outside consultants or OEM make program changes too.
Last date EEPROM Burned	Should be saved to EEPROM (Burned) after every successful program change.
Date battery last changed	See manufacturer’s data for recommended change frequency.
Other information you may need	Might be facility location when corporate HQ is using this form.

Once you have collected the basic information in your Plant wide and/or corporate audit, you need to analyze the information to develop an action plan based on risk analysis. In the risk analysis, bottlenecks and other factors will help you assess priorities. Starting with the highest priority PLC, you will need to ask more important questions.

Do we have the most common spares for the PLC?
Is the OEM (Original Equipment Manufacturer) available 24/7? Or even in business any more?
Do we have a back up copy of the PLC program?
Does our program copy have descriptions so we can work with it reliably and efficiently?
Do we have the software needed to view the PLC program? Are our maintenance personnel trained on that PLC brand?

These are some of the questions our managers must ask, to avoid unnecessary risk and to insure reliability.