AutoCAD Electrical 2021 – Drawing a PLC Rack, Slot & Sub-Slot Within the Schematic Drawings

by Miles Nicholson

In some industries, it is quite popular to draw individual inputs or outputs as separate symbols being drawn on the schematic that they are controlling. In addition to drawing the individual I/O, some clients ideally like to repeat the information of the I/O in a schematic displaying the slot. In an intelligent CAE system, this is effectively duplicating the I/O. In addition the slot is repeated again in a “top down” view of the rack with slots (still within the schematics) duplicating the slot again.

So how can this be achieved without duplicating the I/O and the slots for reporting purposes?

Utilising one of the standard symbols out of one of the IEC libraries as a starting point, a new analogue input was created:

An individual I/O utilises the Edit PLC dialogue so that address, descriptions etc can be assigned and kept track off. The PLC tag being specific to the slot rather than the rack.

A PLC slot was created as a “DN” category component as the Edit PLC dialogue wouldn’t be required for simply the power connections:

The symbol was edited so that cross reference information only displayed the sheet and grid reference of the individual I/O:

This is done by Edit Component >  Component Override >

If you then want a list of the individual I/O being displayed within or next to the slot, a PLC Component Connection report can be run:

With  Special breaks on Installation/Location PLC Tag selected:

..and the report

The slot that’s displayed in the schematic representation of the rack (not footprint) is drawn as a child “DN” category component. This is linked to the parent “DN” category slot above:

The rack being drawn as a parent DN category component but with the tag being specifically unique to the rack:

Finally with the slot being positioned, our schematics now result in:

The sample project can be downloaded from:

Sample PLC Project

For further training on AutoCAD Electrical, please visit our training website: https://training.cadline.co.uk/autocad-electrical/