#7 PLC Best Practices – Validate and Alert for Paired Inputs/Outputs
Alarm the operator when input/output states occur that are physically not feasible. Validate and alert for paired inputs/outputs in PLC.
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#6 PLC Best Practices – Validate Timers and Counters
If timers and counters values are written to the PLC program, they should be validated by the programmable logic controller.
#5 PLC Best Practices – Cryptographic and Checksum Integrity Checks
Use cryptographic hashes, or checksums to check PLC program integrity and raise an alarm when they change.
#4 PLC Best Practices – Use PLC Flags as Integrity Checks
One of the best PLC best practices is to use PLC flags as integrity checks. Put counters on PLC error flags to capture any math problems.
#3 PLC Best Practices – Leave Operational Logic in the PLC wherever feasible
Leave as much operational logic e.g., totalizing or integrating, as possible directly in the PLC. The HMI does not get enough capacity.
#2 PLC Best Practices – Track Operating Modes
Track PLC operating modes – Keep the PLC in RUN mode. If PLCs are not in RUN mode, there should be an alarm to the operators.
#1 PLC Best Practices – Split PLC Code into Modules
#1 PLC Best Practices – Split PLC code into modules, using different function blocks (sub-routines). Test program modules independently.
Principle of Operation of PLC
To understand the PLC working process, let’s take one simple example application is to turn ON a lamp using one push-button and stop button.
PLC Sizes and Applications
In this article, we will discuss the selection criteria of a PLC system, different sizes of PLC systems, and their applications.
Step by Step Guide for Gas Flow Meter Calibration
A gas flow meter device must be calibrated against a reference or a master calibration system as per the standards.