TP177 Micro Standby and Screen Saver Configuration Guide

The Siemens SIMATIC TP177 micro 6-inch HMI panel is a compact, low-cost operator interface built on Windows CE. Unlike a true industrial PC, the TP177 micro does not expose a hardware standby or sleep state to the application layer. The only available power-saving mechanism is the Windows CE Screen Saver, which blanks the backlight after a configured idle interval. This article documents how to access and configure that screen saver through the panel's native Control Panel, the project-level settings available in WinCC flexible, and the operating constraints imposed by the Windows CE image shipped on the device.

1. Overview

The TP177 micro is one of the smallest members of the SIMATIC HMI 170/177 family and is delivered in two display variants:

Both variants run a customized Windows CE image (typically CE 5.0 / HMI image V1.x) and are programmed with WinCC flexible 2004 SPx, WinCC flexible 2007, WinCC flexible 2008 SPx, or TIA Portal (WinCC Comfort/Advanced as of V11). The operating environment exposes a subset of the standard Windows CE shell:

• Boot loader menu (Transfer / Start / Control Panel / Taskbar)
• Control Panel applet for screen, network, date/time, screensaver, regional settings, and system information
• WinCE Start menu with file explorer and a soft keyboard

The screen-saver is the only configurable power-management feature exposed at the CE shell level. There is no ACPI S1/S3 equivalent on this panel.

2. Prerequisites

Before configuring the standby / screen-saver behavior, verify the following:

1. The TP177 micro is powered from a 24 V DC supply capable of delivering at least 1 A (typical power draw: 10 W color, 7 W mono). The panel is not designed for hot-swap of input voltage.
2. A USB or RS-232/PPI programming cable is available (Siemens 6ES7901-3DB30-0XA0 USB-PPI, or 6AV6671-1CB00-0AX2 serial transfer cable). The PC running WinCC flexible must be at the panel's configured transfer channel (default: MPI/DP at 187.5 kbit/s or Ethernet where fitted).
3. Access to the panel's Start menu — either by touch on the deployed screen saver icon, or by tapping the file-explorer icon, or by holding the finger on a blank area of the screen to invoke the Windows CE taskbar.
4. Documentation set: SIMATIC HMI TP177micro Operating Instructions (WinCC flexible).
5. If the panel has been password-protected against Control Panel access, the relevant transfer or maintenance password must be known. Passwords configured under Control Panel > Security are stored in the registry hive and are not retrievable without a full image restore.

3. Accessing the Control Panel

Two independent methods exist for opening the Windows CE Control Panel on the TP177 micro.

3.1 Method A — Boot menu

1. Apply 24 V DC. The panel performs its Power-On Self-Test (POST); the Siemens logo appears for approximately 5–7 seconds.
2. When the loader menu appears, tap Control Panel. The standard WinCE Control Panel window opens.
3. Double-tap the Display applet (icon labelled Display, not Screen Saver). The Display properties dialog contains a Screen Saver tab on the TP177 micro image.

3.2 Method B — Runtime via Start menu

1. In the running project, tap the soft-key or button that is bound to the system function OpenControlPanel (WinCC flexible) or OpenScreenSaverSettings where configured. By default this is not in the project; see section 7.
2. If a taskbar is enabled in the project (Device > Properties > Taskbar in WinCC flexible, checkbox Activate taskbar), the user can tap Start > Settings > Control Panel directly.

4. Configuring the Screen Saver

Within Control Panel > Display > Screen Saver, the following fields are available on the TP177 micro image:

Procedure:

1. Open Control Panel as described in section 3.
2. Open Display.
3. Click the Screen Saver tab.
4. Set Wait to the desired idle interval. For operator-panel use, 5–10 minutes is the typical setting; values below 2 min are intrusive and can interfere with hands-off trend displays.
5. Choose a screen saver. For most industrial deployments, None (no animation, just backlight-off) is preferred to avoid distractions.
6. Tick Password protected only if a system password has been configured elsewhere on the panel; otherwise the option is greyed out.
7. Click OK and reboot the panel from the boot menu to persist the setting (WinCE persists Display settings to the registry, but a power cycle confirms persistence).

The configured timeout is stored in the registry under [HKEY_CURRENT_USER\ControlPanel\Desktop\ScreenSaveTimeOut]. The value is a DWORD in seconds. Manual edits from a CE remote-registry session (e.g. via cerdisp or cepmgr from the Windows CE Platform Builder tools) can be performed but are not supported by Siemens on this device class.

5. What the Screen Saver Actually Does

On the TP177 micro, the screen saver is implemented as a software module on top of the CCFL inverter driver. When activated it performs the following sequence:

1. The WinCE shell invalidates the current display context.
2. Graphics subsystem transitions to a low-paint mode (the chosen saver animation runs at <5 FPS).
3. After an additional backlight-off grace period (image-dependent, default 30 s after the saver starts) the inverter is commanded off via GPIO. The lamp current falls to zero, the panel becomes dark.
4. Touch is still polled. A tap resumes the saver and redraws the previous runtime view.

The result is a backlight-off, CPU-running state. The WinCE image does not halt the kernel, does not suspend polling of MPI/Profibus, and does not drop the HMI-tag acquisition thread. Communications to the S7-200, S7-300, S7-400, or LOGO! PLC are uninterrupted. For this reason the screen saver is the practical equivalent of "standby" on this device.

6. Firmware / Image Constraints

The available screen-saver choices depend on the Windows CE image version flashed into the panel. Siemens released the following image updates under the HMI image umbrella:

To identify the installed image:

1. Open Control Panel > System > General.
2. Read Operating System (e.g. Windows CE 5.00) and Image Version.

The image is updated via ProSave or via a TIA Portal / WinCC flexible transfer. Refer to the SIMATIC HMI Panel Image Update knowledge-base entry for the supported update sequence. Updates are non-reversible on the TP177 micro because the device does not expose a service-mode flash — the update package overwrites the entire image partition.

7. Project-Level Settings in WinCC flexible

The screen-saver behavior is split between the WinCE shell (section 4) and the WinCC flexible project. Project-relevant settings are located in the device editor:

1. In the WinCC flexible project tree, open Devices > TP177 micro > Properties.
2. Switch to Display tab. The following fields are exposed:

3. Switch to Tools tab to set the Password for Control Panel (system password). This is the password that protects the screen-saver resume as well as every other applet.

When the project is compiled and transferred, the settings are written to the device registry and the Control Panel Display > Screen Saver tab reflects the values on next boot.

8. Verification Procedure

After configuring the screen saver, verify the setting by performing the following steps from the operator's perspective:

1. Power-cycle the panel and start the runtime project.
2. Note the system time. Do not touch the panel.
3. Wait the configured interval (e.g. 5 minutes). The screen saver animation should engage.
4. Continue waiting for the backlight-off grace period (≤30 s). The panel should appear fully dark.
5. Tap the screen. The panel should redraw the last runtime view within 1–2 seconds. Tag updates should resume without a re-connection to the PLC.
6. Verify in the PLC's online diagnostics (e.g. STEP 7 monitor) that the OP connection to the TP177 micro is still in Established state — the connection must not have dropped during the standby period.

If the backlight does not extinguish, check:

• Display > Backlight settings — some images expose a Backlight timeout independent of the screen saver. Set this to 1 minute for an immediate verification.
• CCFL inverter fuse on the back of the panel (color variants only). A blown fuse causes the lamp to never strike, even though the screen saver engages.
• Image version. Images older than V01.01.00 do not implement the backlight-off grace period correctly.

9. Troubleshooting Matrix

10. Power and Thermal Considerations

The TP177 micro is rated for 0–50 °C operation (color) and 0–55 °C (mono). With the backlight extinguished, the panel dissipates roughly 30–40 % less heat. For sealed enclosures this is meaningful; in most cabinet layouts the panel's contribution is below 10 W and is dwarfed by the supply, contactors, and drives.

These values are taken from the operating instructions and are nominal. Actual consumption depends on ambient temperature (inverter efficiency drops above 40 °C) and on the percentage of white pixels on screen.

11. Comparison with Successor Panels

If the application requires a true low-power state — for example, a battery-backed island panel that wakes on a discrete input — the TP177 micro is the wrong device class. The successor TP177A (article number 6AV6642-0DC01-1AX1) and the Comfort panels (TP700 / TP900 / TP1200 / TP1500) add a real standby function via the SetScreenSaverTimeout and GoToStandbyMode system functions. The Comfort panels additionally support scheduled wake events and a configurable backlight brightness curve.

For new designs where standby is required, the engineering decision should be made at the device-class stage — not retrofitted through screen-saver workarounds on the TP177 micro.

12. Field-Commissioning Checklist

1. Record the installed image version on the as-built documentation.
2. Configure the screen-saver timeout to a value that matches the operator's standard pause (5–10 min typical).
3. If password protection is enabled, document the password in the project's secure credentials store — not in the operator manual.
4. Verify that the HMI-tag acquisition continues while the saver is engaged. Monitor the connection status tag in the PLC.
5. Verify the resume action: tap → return to previous screen → no login prompt unless password protection is on.
6. Confirm the backlight-off grace period by visual inspection. Adjust if image is older than V01.02.00.
7. Update the project's FMEA / operator training material to reflect that "standby" on this device means "backlight off, PLC connection live."

13. Frequently Asked Questions