A C-more pushbutton configured as Set On writes a 1 when touched and does not send a 0 when released; Set Off writes a 0 and does not send a 1 on release. If an operator expects either button to behave like a spring-return momentary control, the PLC command can appear to remain asserted.
Stop repeating the wrong button action
When a command stays on, repeatedly tapping the same Set On object will keep requesting the on state; it will not generate a release-to-zero command. The same applies in reverse to Set Off: releasing it does not restore a 1. These modes are state-setting commands, not momentary pulses.
- Do not use Toggle as a substitute for a known off command. Toggle reads the current PLC memory state and writes the opposite state. If the displayed or PLC state is stale, or another source changes the tag, the resulting action may not match the operator's expectation.
- Do not switch to Momentary just to clear a maintained command unless the intended PLC behavior is a press-and-release signal. Momentary writes 1 while pressed and 0 when released, which may be wrong for a maintained run/stop request.
- Do not assume releasing Set On or Set Off undoes the command. Use the opposite set command only when the tag and machine state make that action safe.
For a safe temporary restore, identify the actual command tag and machine condition first. If the command is confirmed and the machine can safely accept the opposite state, use the corresponding Set Off or Set On object. If the bit's purpose or downstream effect is unclear, stop rather than probing with live commands.
Read each C-more object mode as a write rule
The HMI does not open or close a hardwired electrical circuit at the PLC input. It writes a value to the PLC memory location associated with the pushbutton tag. The mode determines which value the object writes and whether it sends a value on release.
| Object mode | On touch | On release | Typical use |
|---|---|---|---|
| Momentary | Writes 1 | Writes 0 | A command that should be true only while touched |
| Set On | Writes 1 | No release-to-0 write | Request or select an on state |
| Set Off | Writes 0 | No release-to-1 write | Request or select an off state |
| Toggle | Reads current state, then writes its opposite | No release-to-original-state write | Invert a state when the current tag state is reliable |
In the described object behavior, the HMI writes when the tag value changes. A Set On touch changes the command to 1; lifting a finger does not change it back. Set Off does the converse. Momentary is the mode that deliberately produces a press/release pair of values.
Choose Set On and Set Off for a deliberate two-command pair
Use Set On and Set Off when operators need separate, explicit commands to request opposite states. A common arrangement is one button that requests on and another that requests off. This is different from a single Toggle button: the operator selects the desired command rather than asking the HMI to infer it by reading and inverting the current state.
These objects do not, by themselves, make a PLC output latch, prove a machine is running, or implement interlocks. They write the associated PLC tag. The PLC program must define how that tag is used, including what permits the machine to start and how it stops. Keep safety functions in the safety-rated control path; an HMI graphic command is not a safety device.
Before using this pair, confirm the PLC tag's meaning. A tag named or displayed as a command may be a request, a mode selection, or an internal logic bit rather than direct feedback. Display actual machine status from appropriate PLC feedback separately from the operator's requested state.
Check the tag and PLC logic before changing the screen
A correct HMI write can still appear ineffective if the PLC logic clears or overwrites the tag, if the object points at a different tag than the logic uses, or if communications prevent the write from reaching the PLC. Conversely, the command tag may change while an interlock or permissive prevents the machine response. Diagnose the path in order:
- Read the pushbutton object's configured tag and mode in the C-more project.
- Monitor that exact PLC memory location while touching the object. Confirm that Set On produces 1 and Set Off produces 0, as intended.
- Watch the value after release. For Set On and Set Off, release should not issue the opposite value; for Momentary, release should write 0.
- Trace the PLC logic that consumes the tag. Check whether logic resets it, gates it with permissives, or uses a separate run/status bit.
- Compare the command value with machine feedback and any available HMI/PLC communication diagnostics.
If the HMI value changes but the PLC does not act, investigate the PLC logic and operating conditions rather than changing object type blindly. If the PLC value never changes, check the tag assignment and communications path before editing machine logic.
Configure the command pair without changing machine logic by accident
Make project edits with the machine in a safe operating condition and with the command's effect understood. Use this sequence for a new or corrected pair:
- Identify the PLC tag intended for the command and verify its data type and use in the PLC program.
- Assign the on-request object to that tag and select Set On. Assign the off-request object to the intended off command tag and select Set Off. If the PLC design uses one tag for both actions, follow that design rather than creating a second command by assumption.
- Check the object text, color/state indication, and tag mapping against the PLC program. Do not make a button's visual state imply feedback unless it is driven by a separate status value.
- Download or deploy the revised project using the site's approved change procedure. Keep a known-good project copy so the screen can be restored if the edit causes an unexpected command.
Separate command and feedback tags where the PLC design provides them. This lets the operator distinguish “requested on” from “confirmed on,” especially when an interlock rejects a command or equipment has not yet reached the requested state.
Verify writes, release behavior, and the machine response
Test the HMI behavior at the PLC tag first, then verify the process response under authorized operating conditions. Do not treat a changing button graphic alone as proof that the PLC received a write or that the machine moved.
- Touch Set On and confirm the associated tag becomes 1.
- Release it and confirm no 0 write occurs from release.
- Touch Set Off and confirm the associated off command becomes 0; release should not write 1.
- If comparing modes, verify that Momentary returns to 0 on release and that Toggle inverts the tag value it reads.
- Check PLC logic status, permissives, and independent machine feedback to confirm the expected response or identify why it was inhibited.
Run the test with the machine state and personnel protected by the site's normal operating controls. If any command behaves differently from its configured write rule, stop testing and inspect the project/tag mapping and PLC logic before returning the control to operators.
Separate a button-mode fault from a machine-response fault
| Observed symptom | Likely area to inspect | Next check |
|---|---|---|
| Command remains 1 after releasing Set On | Expected Set On behavior | Use a deliberate off command if safe; do not expect release to clear it. |
| One Toggle press produces an unexpected state | Current tag value, stale display, or another writer | Monitor the PLC value and confirm the object is reading the intended tag. |
| HMI indicates a command but PLC tag does not change | Tag mapping, data connection, or write path | Verify the exact object tag and review communication diagnostics. |
| PLC command tag changes but equipment does not respond | PLC logic, permissives, or separate output/status path | Trace the consuming logic and compare with machine feedback. |
| Momentary command remains active after release | Wrong object mode, tag mapping, or another writer | Confirm mode and monitor the PLC tag through press and release. |
Do not mask a PLC logic or communications fault by changing the button to another mode. Restore production temporarily only when the correct command and safe machine response are confirmed; make the permanent repair in the HMI project, PLC logic, or communications configuration that the checks identify.
FAQ
What happens if I release a C-more Set On button?
The HMI does not send a 0 merely because you released the object. The associated PLC tag remains at its written value unless PLC logic or another write changes it.
What happens if I use Set Off instead of Toggle?
Set Off explicitly writes 0 on touch and does not write 1 on release. Toggle reads the current state and writes its opposite, so use Set Off when the required command is specifically off.
What happens if the PLC tag changes but the machine does not respond?
Check the PLC logic that consumes the tag, its permissives, and independent machine feedback; the HMI write alone does not prove the equipment accepted the request. Stop and escalate to AutomationDirect official support if the C-more object or communication behavior remains inconsistent after confirming the project tag and PLC value, and provide the project and observed diagnostics.