Siemens 6AV6355-1AA47-7EC1 OP 77A

SKU: 6AV6355-1AA47-7EC1 Category: HMI & Display Brand: Siemens

Description
Additional information

The Siemens 6AV6355-1AA47-7EC1 is an operator panel belonging to the SIMATIC HMI OP 77A series, designed for machine-level human-machine interface applications. This compact panel provides a keypad-based interface for process visualization and operator control, and is part of Siemens' SIMATIC HMI product line. It is intended for use in environments where a robust, panel-mounted operator interface is required without the need for a full touchscreen display.

The OP 77A features a monochrome LCD display and a membrane keypad with function keys, system keys, and alphanumeric input capability. It communicates via MPI and PROFIBUS DP interfaces, enabling direct integration with SIMATIC S7 PLCs. The unit operates on 24 V DC supply voltage and is built to withstand industrial environments, carrying an IP65 protection rating on the front panel. Configuration is performed using Siemens WinCC flexible software.

The OP 77A is commonly deployed on machine tools, packaging machinery, conveyor systems, and general factory automation equipment. Its compact form factor and keypad-based operation make it suitable for applications where space is limited and touchscreen interaction is not required. The panel is widely used in discrete manufacturing and process industries where reliable, straightforward operator control is essential.

Technical Specifications

Display Type	Monochrome LCD
Display Size	4 lines x 20 characters
Input Voltage	24 V DC
Voltage Tolerance	19.2 V DC to 28.8 V DC
Power Consumption	Approx. 4 W
Communication Interface	MPI, PROFIBUS DP
IP Rating (Front)	IP65
IP Rating (Rear)	IP20
Operating Temperature	0 °C to 50 °C
Storage Temperature	-20 °C to 60 °C
Relative Humidity	10% to 90% (non-condensing)
Mounting	Panel mounting
Certifications	CE, UL
Configuration Software	WinCC flexible 2005 or higher

Common Error Codes & System Events

Event ID: 10000: Communication error between the OP 77A and the connected PLC. The panel cannot establish or maintain a connection to the configured controller.
Check MPI or PROFIBUS DP cable connections and termination resistors. Verify the PLC address settings match the panel configuration. Ensure the PLC is powered and in RUN mode.
Event ID: 10001: Timeout error on the communication link. The panel did not receive a response from the PLC within the expected time frame.
Check network cabling for damage or loose connectors. Verify baud rate settings on both the panel and PLC. Reduce network cable length or check for excessive bus loading.
Event ID: 20000: Project download error. A fault occurred during the transfer of the configuration project to the panel.
Verify the PC-to-panel connection (MPI or USB adapter). Ensure WinCC flexible version is compatible with the panel firmware. Retry the download and check available panel memory.
Event ID: 40000: Tag read error. The panel is unable to read a configured tag from the PLC.
Verify the tag address in the WinCC flexible project matches the actual PLC data block or memory area. Confirm the PLC program contains the referenced address.
Event ID: 40001: Tag write error. The panel is unable to write a value to a configured PLC tag.
Check that the target PLC address is not write-protected. Verify the tag configuration in WinCC flexible and confirm the PLC is in a state that allows external writes.
Event ID: 50000: System memory low. The panel's available runtime memory is insufficient for the loaded project.
Reduce the number of active alarms, screens, or logged data in the project. Simplify the project configuration and re-download to the panel.
Communication Error: No connection to PLC at startup. The panel displays a connection error on boot before the project loads.
Verify MPI/PROFIBUS address configuration on the panel matches the PLC. Check that the PLC is powered and the bus cable is properly connected with correct termination.

Frequently Asked Questions

What PLCs are compatible with the OP 77A?

The OP 77A is compatible with Siemens SIMATIC S7-200, S7-300, and S7-400 PLCs via MPI or PROFIBUS DP. It can also communicate with S7-200 via PPI protocol depending on configuration.

What software is used to configure the OP 77A?

The OP 77A is configured using Siemens WinCC flexible 2005 or later versions. Projects are downloaded to the panel via an MPI adapter or PC/PPI cable.

What is the supply voltage for the 6AV6355-1AA47-7EC1?

The panel requires a 24 V DC supply voltage, with an acceptable range of 19.2 V DC to 28.8 V DC.

What is the front panel protection rating of the OP 77A?

The front panel of the OP 77A carries an IP65 protection rating, making it suitable for environments where dust and water jets may be present.

Can the OP 77A display graphics or only text?

The OP 77A uses a character-based monochrome LCD display and is primarily designed for text-based operator interaction. It does not support graphical screen layouts in the same way as graphical HMI panels.

Troubleshooting

Display remains blank after power on

Check the 24 V DC supply voltage at the panel power connector. Verify the voltage is within the 19.2 V to 28.8 V range. Inspect internal fuse if accessible.

Restore correct supply voltage. If voltage is correct and display remains blank, the panel's internal power supply or LCD backlight may have failed and the unit requires repair or replacement.

Panel shows 'No connection to PLC' message at startup

Verify MPI or PROFIBUS DP cable is securely connected at both the panel and PLC ends. Check that bus termination resistors are correctly placed at both ends of the network segment.

Correct any wiring faults, ensure proper termination, and confirm that the PLC address configured in the WinCC flexible project matches the actual PLC station address. Restart the panel after corrections.

Project download fails from WinCC flexible

Check the PC-to-panel communication cable and adapter (MPI/USB adapter or PC/PPI cable). Verify that the correct communication port and baud rate are selected in WinCC flexible transfer settings.

Replace or reseat the communication cable. Set the correct COM port and baud rate in the transfer dialog. Ensure the panel is in transfer mode before initiating the download.

Function keys do not respond to presses

Inspect the membrane keypad for physical damage, contamination, or deformation. Test each key systematically to identify whether the fault is isolated to specific keys or affects all keys.

Clean the keypad surface if contamination is present. If keys are physically damaged or the membrane has failed, the keypad membrane assembly requires replacement.

Alarm messages are not displayed on the panel

Verify that alarm tags are correctly configured in the WinCC flexible project and that the corresponding PLC bit addresses are active. Check that the alarm view or alarm line is included on the relevant screen.

Correct the alarm tag addresses in the project configuration and re-download the project. Ensure the PLC program is setting the correct alarm bits and that the panel project is up to date.

Condition	Repair, Used, Refurbished, New in box (sealed)