For 3-phase motors, the Caterpillar controls a variable-frequency drive (VFD) through its digital inputs (DIx), driven by relays on our relay expansion board—a convenient way to get run/stop and direction control without any serial link. Any VFD that lets you assign run/stop and forward/reverse commands to digital inputs can be used this way; the parameter names and numbers below are given for the WEG CFW300 as a concrete example—consult your VFD's manual for the equivalent digital-input parameters if you are using a different model.
For the VFD to read its digital inputs the way the Caterpillar's relays expect, a few parameters have to be adjusted. On a CFW300, these are:
| Param | Description | Value | Meaning |
|---|---|---|---|
| P220 | LOC/REM Selection Source | 4 | DIx (0 always LOC, 1 always REM) |
| P223 | LOC FWD/REV Selection | 4 | DIx |
| P224 | LOC Run/Stop Selection | 1 | DIx |
| P263 | DI1 Input Function | 9 | LOC/REM |
| P265 | DI3 Input Function | 4 | Forward Run |
| P266 | DI4 Input Function | 5 | Reverse Run |
After this configuration, the VFD will obey the run/stop and direction relays wired from the expansion board's outputs to its digital inputs, and will also be capable of manual operation with the flip of a switch.
Need: wiring diagram showing expansion board relay outputs to VFD digital input terminals, and which digital inputs (CFW300 numbering or otherwise) should be used for run/stop and direction.