The EZ-Touch lamp saver turns the display off, but the PLC needs to wake it without an operator touching the panel. The practical method is to command a different valid screen, confirm that the panel displayed it, then command the original screen.
Stop repeating the current screen number
A PLC-to-Panel screen command only wakes the panel when the requested screen number changes from the current screen. Writing the same value again does not create a screen change, so it does not wake the display. A command for a nonexistent screen is not a substitute: the panel may ignore it, leaving the display asleep.
| What you see | Likely cause | Correction |
|---|---|---|
| PLC writes the displayed screen number, but the lamp stays off | The command value did not change. | Command a different valid screen number. |
| PLC writes a screen number that has no configured screen | The requested screen is invalid and may be ignored. | Use a valid alternate screen, then return to the original. |
| Panel displays the alternate screen but does not return | The return command was issued before the panel reported the screen change, or the PLC reused an unchanged value. | Wait for Panel-to-PLC feedback to show the alternate screen before writing the original screen number. |
Do not troubleshoot this as a failed screensaver setting first. The key distinction is between writing a screen value and causing a change to a valid screen.
Configure both screen-number directions
Set up the EZ-Touch project so the PLC can command a screen and the panel can report which screen it is displaying. In the editor, configure Setup > Project Attributes > PLC to Panel > Switch to Screen Number with the PLC memory location used for screen-change commands. Then configure Setup > Project Attributes > Panel to PLC > Current Screen with a location for the panel's current-screen value.
Using the same V-memory location for both directions was reported as workable, but separate locations make command and feedback easier to distinguish in the PLC program. Whichever arrangement you choose, confirm the configured addresses and data format in the project and PLC before commissioning.
Check: With the panel awake, observe the Panel-to-PLC Current Screen value while displaying a known screen. It should report that screen number. If it does not, correct the project attributes or address mapping before building wake logic.
Add a valid alternate screen
If the project has only one screen, add a second valid screen. It can be blank or identical to the operating screen; the purpose is to provide a different valid destination that forces a screen transition. Record both screen numbers and use those exact configured values in the PLC program.
Do not use an arbitrary number merely because it differs from the current screen. The panel must have a valid screen at that number for the change-and-return sequence. An invalid target can be ignored and gives the PLC no reliable transition to confirm.
Check: Use the panel's normal screen-change function to display the alternate screen, then return to the operating screen. Confirm that both screens render acceptably and that Current Screen reports each number in turn.
Sequence the wake and return commands
On a wake request, command the alternate screen first. Wait until Panel-to-PLC Current Screen equals the alternate number; that feedback indicates the panel has switched to it. Then command the original operating screen and wait for feedback to equal the original number. Do not issue both writes back-to-back without checking feedback, because the panel may not have processed the first transition before the second command arrives.
- Latch or otherwise retain the wake request long enough for the sequence to complete.
- Write the alternate screen number to the PLC-to-Panel command location.
- Wait until the Panel-to-PLC Current Screen value equals the alternate screen number.
- Write the original screen number to the PLC-to-Panel command location.
- Wait until Current Screen reports the original number, then clear the sequence state.
Use the PLC's normal state or step logic to prevent a new write every scan from overwriting an in-progress transition. If an operator can change screens during the sequence, decide whether the PLC should cancel the wake routine or restore a fixed operating screen; avoid silently fighting operator navigation.
Check: Trigger the sequence while the display is in lamp saver mode. Confirm that feedback reports alternate, then original, and that the lamp is on with the intended operating screen visible.
Use a sentinel only as a controlled alternative
A second reported method writes K9999 to the PLC-to-Panel screen location after the Panel-to-PLC current-screen value matches the command value. Because the sentinel is intended to be an invalid screen number, the panel is expected to ignore it; the next valid screen command then differs from the command register's value and can trigger a change. This method avoids adding a blank screen, but it depends on the panel ignoring that invalid value as expected.
Another reported approach loads KFFFF after a five-second timer completes. It was suggested as a way to make the next screen command differ, but a timer-based write does not itself prove that the panel processed a screen transition. Prefer the valid alternate-screen sequence with feedback when possible. If using either sentinel approach, test it on the actual panel and project before relying on it in production, and prevent the sentinel from being treated elsewhere as a real screen command.
Check: Monitor both PLC memory locations during a controlled test. Verify the sentinel is followed by a valid command, that the displayed screen changes as intended, and that the PLC does not leave the panel at an unintended screen.
Separate a no-timeout fault from the wake sequence
A separate reported behavior involved a screen that would not enter lamp saver mode, even though similar screens did. The test screen included indicator lights tied to X0, X1, X2, Y0, Y1, and Y2, a bar graph at V0000, meters, text, and screen-related objects. The behavior continued in a test with programming software off and the PLC and panel on. A hypothesis that a connected programming computer affected timeout behavior was raised, but it was not confirmed; a technician could not reproduce the problem using separate test files or the supplied files.
Keep this symptom separate from a panel that sleeps correctly but will not wake on a repeated screen number. For a timeout problem, test the panel without the programming computer connected, compare a minimal screen against the affected screen, and verify lamp-saver project settings. If the issue persists, record the exact panel, software, and firmware versions and the screen objects present; the reported tests did not isolate a definitive object or software cause.
Power was also raised as a possible factor. One test installation reported a dedicated PS24-050D supply measuring 24.0 V while powering the panel, with no change after analog I/O modules were removed or after applying 24 V before connecting the panel. A technician stated that the panel must have 1.2 A available at startup and suggested removing other loads from the supply as a test. Treat this as a startup capacity check, not as a proven explanation for the no-timeout symptom.
Check: Confirm the panel's startup supply capacity against its documentation and test with other supply loads removed if applicable. If the screensaver still fails to time out, preserve the reproducible project and version details for escalation rather than changing the wake sequence at random.
Verify the complete operator-free cycle
Commission both behaviors independently: lamp saver must activate after the configured inactivity period, and a PLC wake request must restore the display through a confirmed screen change. Test from the original operating screen, trigger the wake sequence, watch both PLC registers, and confirm the panel returns to the intended screen. Repeat after an operator-selected screen change so the PLC does not assume the original screen number is still active.
Confirm the PLC handles stalled feedback without issuing uncontrolled repeated commands. Add a fault or timeout response based on the site's control design, and expose the last command and Current Screen values in diagnostics. Do not claim a successful wake solely because the PLC wrote a value; verify the panel's reported current screen and visible display.
FAQ
Why does writing the same EZ-Touch screen number not wake the display?
The panel responds to a screen-number change, not a repeated write of the already active number. Command a different valid screen and verify the transition through the Panel-to-PLC Current Screen value.
Why does an invalid EZ-Touch screen number fail to wake the lamp?
An invalid target can be ignored, so no valid screen transition occurs. Add a blank or identical valid screen and use it as the alternate destination before returning to the operating screen.
How do I read the current EZ-Touch screen number in the PLC?
Configure Setup > Project Attributes > Panel to PLC > Current Screen with a V-memory address, then monitor that address in the PLC. It should report the number of the screen currently displayed.
Stop commissioning and contact AutomationDirect official support if the configured feedback does not track known screen changes, a valid alternate-screen sequence fails on the panel, or the lamp saver remains abnormal after isolated testing. Provide the project, PLC logic, panel and software/firmware versions, power-supply details, and the observed command and Current Screen values.