In industrial automation, the words permissive and interlock are often used as if they mean the same thing.
They do not.
Both are conditions that influence whether equipment is allowed to operate, …
Read MoreIntroduction
One of the best ways to improve PLC programming skills is to stop thinking only in terms of individual instructions and start thinking in terms of process behavior, equipment states, …
Read MoreThere is a message becoming increasingly common in industrial automation:
Take a PLC course, learn ladder logic, become a PLC programmer, and start making great money.
There is some truth inside that …
Read MoreIn industrial automation, the word alarm is often used for almost everything that goes wrong.
A motor fails to start.
A tank reaches a high level.
A VFD trips.
A communication module disconnects.
An operator …
Read MoreA PLC program can work perfectly and still be difficult to troubleshoot.
That distinction matters.
When we first learn ladder logic, the goal is usually simple:
Make the motor run.
Later, the goal becomes …
Read MoreOne of the most useful PLC programming patterns a technician can learn is also one of the simplest:
Trigger → Hold-In → Interrupt
The idea is straightforward.
Something starts the action.
Something keeps it …
Read MoreIn industrial PLC programming, there are often several ways to make the same machine work.
Two of the most common methods for maintaining a control condition are Seal-In logic and Latch/Unlatch …
Read MoreIn the first article of this series, we introduced the idea of separating physical PLC I/O from application logic.
Now we can address one of the most common questions in Allen-Bradley …
Read MoreIn the previous article, we built a complete digital I/O architecture.
Digital signals are relatively simple:
0 = OFF
1 = ON
Analog signals are different.
An analog input may represent:
Tank level
Pressure
Temperature
Flow
Speed
Weight
pH
Conductivity
Valve position
Motor current
Instead of …
Read MoreThroughout this series, we have examined several ways to build an I/O architecture in Studio 5000:
Direct I/O
Alias Tags
Individual Mapping
MOV
COP
CPS
UDTs
Each method offers different architectural advantages.
But eventually someone asks:
Which method is fastest?
Or:
Which …
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