Automation Programming
What we do
PLC programming and SCADA work are covered together here because, on most plants, they are the same job seen from two ends. A sequence change in the PLC needs the screens, alarms and tags in SCADA to match, and a new SCADA screen is only as good as the PLC data behind it.
Typical requests are a machine that needs a sequence change, an interlock or alarm that misbehaves, a plant that wants production data on a screen or in a report, and an old PLC or SCADA platform that can no longer be supported. Before any change, the existing program and project are backed up; plants often have no current copy, and getting one is the first useful thing a visit does.
Upgrades and new SCADA systems are rolled out in stages where production allows. Data collection can run alongside the existing system until the readings agree, and only the switch-over of direct control needs a planned stop.
Scope
What's covered
- PLC logic changes, fault finding and online edits on running machines
- SCADA screens, alarms, trends and reports built around operator tasks
- Communication between PLCs, drives, HMIs and SCADA over common protocols
- Migration from obsolete PLC or SCADA platforms with existing logic preserved
- Alarm clean-up so operators see the alarms that matter
- Program and project backups, with documentation of every change
Questions
SCADA & PLC Programming: common questions
Can PLC changes be made without stopping the machine?+
Many PLCs allow online edits, so small logic changes can be made while the machine runs. Larger changes, or anything affecting safety interlocks, are tested and done during a planned stop. The existing program is always backed up first.
Our PLC or SCADA system is obsolete. Do we have to rewrite everything?+
Usually not. The existing logic and screens can normally be converted to a current platform and then checked, rather than rewritten from scratch. Conversion keeps the behaviour operators know, and the check catches anything that doesn't translate directly.
Will we lose historical data when SCADA is upgraded?+
Not if it is planned for. Historical data can usually be exported from the old system and imported into the new historian, though tag names or resolution may change. What can be carried over is confirmed before the upgrade starts.
We have no copy of our PLC program. Is that a problem?+
It is a risk worth fixing. If the program can still be read from the PLC, it is uploaded and saved before any other work. A PLC that fails with no backup means rebuilding the logic from the machine's behaviour, which takes far longer.
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Written & reviewed by MachineryFix
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