When working with Allen-Bradley ControlLogix or CompactLogix systems, one of the first architectural decisions a programmer eventually faces is how to handle physical I/O inside the PLC program.
At the beginning, …
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 compared three common ways of representing PLC I/O:
Direct physical I/O
Alias Tags
Mapped controller tags
Now it is time to build the mapping layer itself.
For digital signals, one …
Read MoreIn the previous article, we built an I/O mapping layer using individual instructions.
For digital signals, we used logic such as:
XIC Physic
al_Input
OTE Internal_Tag
For numeric values, we introduced:
MOV Source Destination
This approach is …
Read MoreIn the previous articles, we built an I/O architecture using:
Direct physical I/O
Alias Tags
Individual mapped tags
XIC/XIO and OTE
MOV
COP
CPS
These methods allow us to separate physical hardware from application logic.
But as the machine …
Read MoreIn the previous articles, we explored several ways to organize and transfer PLC data:
Direct I/O
Alias Tags
Individual Mapping
MOV
COP
CPS
UDT-Based Architecture
Now we can bring those concepts together and build a complete digital I/O …
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 MoreIn the previous article, we followed an analog signal from a field transmitter into the PLC:
Field Instrument
↓
Analog Input Module
…
Throughout 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 …
Read MoreThroughout this series, we have explored several different ways to handle I/O in Studio 5000.
We started with the simplest possible approach:
Local:1:I.Data.0
Then we introduced:
Alias Tags
Individual Mapping
MOV
COP
CPS
UDTs
Digital I/O Processing
Analog Scaling
Analog Output Processing
Performance …