When logged in, Automation Builder shows live values in every editor: energised contacts and coils are highlighted in ladder. To change a value, type the new value in the prepared value field, then use Write values to set it once, or Force values to hold it against the program and I/O until you release the force. Always release all forces before leaving the machine.
- Write = set once, the program can overwrite it next scan
- Force = hold the value against the program and the field until released
- Use a watch list per test so you are not scrolling through POUs
- A forced output can start a motor: isolate first and release all forces at the end
Monitoring is the most used function in commissioning. Forcing is the most dangerous. Learning both on a trainer is the right order.
Step 1: Monitor the Ladder Online
- Log in and open the start/stop POU.
- Press Start on the kit and watch the rung: closed contacts and the energised coil are highlighted.
- Hover over a variable or look at the value shown next to it.
- Open the I/O Mapping tab of the DX561 online and press the jog buttons: values change live.
Monitoring view: write vs force
Use the Start button as normal. Then try “Write” and “Force” on DO_Motor_Run and see how the program reacts.
Green contact = passing power. Orange moving wire = rung is true and the output is energised.
Notice that a written TRUE is kept here only because the seal-in contact holds it, and Stop clears it at once. A forced TRUE ignores Stop completely. That is why forces are dangerous.
Step 2: Build a Watch List
- Open the watch window (V2: Watch and Recipe Manager; V3: Watch 1).
- Add the variables below, one per line.
- Name the list
WL_StartStopso it can be reused in the FAT.
| Variable | Type | What you look for |
|---|---|---|
| DI_Start_PB | BOOL | TRUE only while pressed |
| DI_Stop_PB | BOOL | FALSE while pressed |
| DI_EStop_OK | BOOL | TRUE when healthy |
| DI_MPCB_OK | BOOL | TRUE when healthy |
| DO_Motor_Run | BOOL | Follows the start/stop logic |
| DI_Contactor_FB | BOOL | Follows DO_Motor_Run within ~100 ms |
Step 3: Write and Force Values
| Action | V2 editor command (typical shortcut) | Effect | Remove with |
|---|---|---|---|
| Prepare value | Double-click the value field, enter new value | Nothing yet | n/a |
| Write values | Online > Write values (Ctrl+F7) | Set once; program may overwrite next scan | Not needed |
| Force values | Online > Force values (F7) | Held every scan, I/O and program ignored | Online > Release force (Shift+F7) |
| Show forces | Forced variables are marked in the editor | Know what is forced | n/a |
Step 4: Monitoring Checklist
| ID | Check | How to check | Pass criterion | Result |
|---|---|---|---|---|
| Monitoring and forcing | ||||
| M-01 | Live rung | Press Start | Rung highlighted, coil energised | |
| M-02 | Watch list | Open WL_StartStop | All 6 variables update | |
| M-03 | Write | Write DO_Motor_Run TRUE then press Stop | Output drops on Stop | |
| M-04 | Force | Force DO_Motor_Run TRUE with motor isolated | Output stays on even with Stop | |
| M-05 | Release | Release all forces | Force list empty, logic normal | |
Practice Exercise
Force DI_EStop_OK to TRUE with the E-stop pressed (motor isolated). Explain why this is never allowed on a real machine, and how the hardwired safety relay still protects people.
Troubleshooting
| Symptom | Likely cause | Fix |
|---|---|---|
| Values not updating | Not logged in or wrong project open | Check login status and project version |
| Written value jumps back at once | Program writes the variable every scan | Expected behaviour; use force only if justified |
| Output still ON after logout | Force not released | Log in again and release all forces |
| Cannot force an input | Function not available in that view | Force from the watch list or variable declaration |
Frequently asked questions
What is the difference between force and write in Automation Builder?
Write sets a value once, and the program can change it in the next cycle. Force holds the value every cycle against the program and the physical I/O until you release it.
Is forcing safe on a running machine?
Only under a controlled procedure with the hazard isolated. A forced output can start equipment that the program would keep off.
How do I remove all forces?
Use Online > Release force (in V2, typically Shift+F7) and check that no variable is still marked as forced before logging out.
Can I monitor without changing the program?
Yes. Logging in to an identical project only monitors; nothing is downloaded.