Macro 19: DI0 = enable/OFF1 (NC STOP), DI1 = START clockwise, DI2 = START counter-clockwise, DI3 = acknowledge. Macro 20: DI0 = enable/OFF1, DI1 = START, DI2 = reverse selection, DI3 = acknowledge. AI0 is the speed in both. A short START press latches the run; STOP removes the enable.
- STOP is NC, because DI0 is an enable.
- START buttons are momentary.
- Reset moves to DI3.
- NC STOP is not an E-stop.
The Pushbutton Cycle: Enable, Start, Stop
Three-wire control suits local panels: a brief press starts, a separate STOP ends. Decide first whether operators need two direction START buttons (macro 19) or one START plus a direction selector (macro 20).
Macro 19 vs Macro 20: Inputs and Behaviour
| CU240E-2 input | Macro 19 | Macro 20 |
|---|---|---|
| DI0 | Enable / OFF1 (NC STOP) | Enable / OFF1 (NC STOP) |
| DI1 | START clockwise (pulse) | START (pulse) |
| DI2 | START counter-clockwise (pulse) | Reverse selection (held) |
| DI3 | Acknowledge | Acknowledge |
| AI0 | Speed reference | Speed reference |
| Typical setting | p3334 = 3 | p3334 = 4 |
Try it: press STOP and the START buttons, or flip the REV selector in macro 20. The demo runs a full cycle until you click.
Simulator: 30 Hz reference, 15 Hz/s ramp. Behaviour for requests during motion follows your firmware’s timing diagram.
Build and test a real pushbutton panel
Hands-on G120 three-wire control with STOP/START panels and PLC integration — Pune or online.
EPLAN Wiring: Macro 19 and Macro 20 Panels
Each macro gets its own sheet, because the same DI2 terminal is a START button in macro 19 and a held direction selector in macro 20.
- Supply and commonsFused PELV L+ goes to 31, and 32 goes to M. DI COM1 (69) and GND (28) go to M.
- STOP as a normally-closed enable-S0 is an NC stop button → DI0. It keeps 24 V on DI0 (enable) until pressed, which requests OFF1. A broken wire also stops the drive. This is an operational stop, not an E-stop.
- Momentary start buttons (macro 19)-S1 START CW → DI1 and -S2 START CCW → DI2 are spring-return NO buttons. A short press starts the drive, and it keeps running after release while DI0 stays closed.
- Reset moves to DI3-S3 RESET → DI3. In three-wire macros DI2 is a command input, so a two-wire panel reused here would make the reset button start CCW. Pot -R2 on AI0, fault relay -H1.
- STOP enable (macro 20)Same NC stop -S0 → DI0 (enable / OFF1).
- One START plus a direction selector-S1 START (momentary) → DI1. -S2 is a maintained REV selector → DI2: open = clockwise, closed = reverse. Select the direction while stopped, then press START.
- Reset, speed and fault-S3 RESET → DI3, pot -R2 on AI0 (screened), fault relay -H1. Label the panel for macro 20, not 19.
| Device | Terminal | Macro 19 | Macro 20 | Check |
|---|---|---|---|---|
| -S0 STOP (NC) | 5 (DI0) | Enable / OFF1 | Enable / OFF1 | r0722.0 = 1 at rest |
| -S1 | 6 (DI1) | START CW (NO pulse) | START (NO pulse) | r0722.1 |
| -S2 | 7 (DI2) | START CCW (NO pulse) | REV selector (held) | r0722.2 |
| -S3 RESET | 8 (DI3) | Acknowledge | Acknowledge | r0722.3 |
| -R2 pot | 1·3·2, link 4–2 | Speed | Speed | r0755 |
| 20 → 19 | -H1 | Fault relay | Fault relay | provoke a fault |
Training drawings for a CU240E-2. Check terminals against the manual for your CU and firmware. Power, EMC and STO: G120 wiring guide.
Why Fault Reset Moves to DI3
Diagnose Common Three-Wire Faults
| Problem | Inspect |
|---|---|
| START has no effect | Enable on DI0, the START transition, data set, drive state |
| RESET changes direction | Reset still wired to DI2 from a two-wire panel |
| Runs only while the button is held | Command routing still two-wire |
| Unexpected behaviour after STOP release | Stuck START, external latch, restart logic |
| Enabled but no speed | AI0 reference, scaling, setpoint path |
Check the raw r0722 bits first. A correct bit with the wrong response points to mapping or sequence; a bit that does not follow the button points to wiring. Compare with two-wire control and analogue speed scaling.
Practical Lab: Verify a Complete Operating Cycle
Hands-on- A G120 with CU240E-2 on a training rig, macro 19 or 20 applied, NC STOP, momentary START buttons, motor uncoupled.
- Record columns: operator action, r0722 bits, expected state, actual state. Estimated time: 40 minutes.
START without enable
Hold STOP pressed and press START.
Fresh start
Release STOP, then press and release START (or START CW).
STOP while running
Press STOP.
STOP released without a new START
Release STOP and do nothing else.
Direction
Macro 19: use START CCW. Macro 20: select REV while stopped, then press START.
Fault and power recovery
Under the approved procedure, trip a fault, acknowledge it on DI3, and power-cycle.
Every operator action produces the expected input bit and drive state, the drive never starts without a fresh START, and RESET acknowledges faults without causing motion.
Frequently asked questions
What is the main difference between macros 19 and 20?
Macro 19 has separate START clockwise (DI1) and START counter-clockwise (DI2) buttons. Macro 20 has one START (DI1) and a reverse selection (DI2). Both use DI0 as enable/OFF1 and DI3 as fault acknowledge.
Why is the STOP button normally closed?
DI0 is an enable: it must stay at 24 V for the drive to run. A normally closed STOP removes the signal when pressed, and a broken wire also stops the drive instead of hiding the fault.
Is the normally closed stop button an emergency stop?
No. It gives an operational OFF1 stop. Emergency stopping needs the machine’s validated safety design, such as STO through a safety relay.
Why did the fault-reset input change to DI3?
In the three-wire presets DI2 is a command (START CCW or reverse), so acknowledge moves to DI3. A reused two-wire panel with reset on DI2 would start the motor instead.
Do I need a self-holding PLC bit for three-wire control?
Usually not. The drive’s three-wire function latches the run state from the START pulse. Adding another latch makes stop and restart harder to diagnose.
Which parameter sets the three-wire method?
The macro sets it, commonly shown as p3334 = 3 (macro 19) or 4 (macro 20). Check the online connections after applying the macro.
Technical references
Use the edition that matches your hardware and firmware. The manuals establish the device facts; the simulators, animations and drawings are training examples.