Siemens 6AV6355-1AA31-8DL6 OP 77A

SKU: 6AV6355-1AA31-8DL6 Category: HMI & Display Brand: Siemens

Description
Additional information

The Siemens 6AV6355-1AA31-8DL6 is an operator panel belonging to the SIMATIC HMI OP 77A series, manufactured by Siemens. It is a compact, key-operated panel designed for machine-level human-machine interface applications, providing operators with a straightforward means of monitoring and controlling automated processes. This unit is part of the SIMATIC HMI product line, which is widely deployed across industrial automation environments worldwide.

The OP 77A features a monochrome LCD display and a membrane keypad with function keys, system keys, and numeric entry keys for direct operator input. It supports the MPI (Multi-Point Interface) and PROFIBUS DP communication protocols, enabling seamless integration with SIMATIC S7-200, S7-300, and S7-400 PLCs. Configuration is performed using Siemens WinCC flexible software, and the panel includes internal flash memory for storing project data and recipes. The unit operates on a 24 V DC supply and is designed to meet IP65 protection on the front panel for use in industrial enclosures.

The OP 77A is typically used in machine building, manufacturing automation, and process control applications where a cost-effective, robust operator interface is required. It is well suited for packaging machinery, conveyor systems, and general-purpose machine control panels. Its compact form factor and keypad-based operation make it appropriate for environments where touchscreen interfaces are not practical or necessary.

Technical Specifications

Display Type	Monochrome LCD
Display Size	4 lines x 20 characters
Input/Operating Voltage	24 V DC
Power Consumption	Max. 5 W
Communication Interface	MPI, PROFIBUS DP
IP Protection Rating (Front)	IP65
IP Protection Rating (Rear)	IP20
Operating Temperature	0 °C to +50 °C
Storage Temperature	-20 °C to +60 °C
Relative Humidity	10 % to 90 %, non-condensing
Configuration Software	WinCC flexible 2005 or higher
PLC Compatibility	SIMATIC S7-200, S7-300, S7-400
Mounting	Panel mounting
Certifications	CE, UL, cULus

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 controller.
Check MPI or PROFIBUS DP cable connections and termination resistors. Verify the PLC address settings match the project configuration. Ensure the PLC is powered and in RUN mode.
Event ID: 10001: PLC address not reachable. The configured PLC station address cannot be found on the network.
Verify the station address configured in WinCC flexible matches the actual PLC address. Check bus cable integrity and termination.
Event ID: 20000: Project download error. A fault occurred during transfer of the project from the configuration PC to the panel.
Check the PC-to-panel transfer cable and connection. Ensure the panel is in transfer mode before initiating download. Retry the download from WinCC flexible.
Event ID: 40000: Internal memory error. The panel has detected a fault in its internal flash memory or project data is corrupted.
Re-download the project to the panel using WinCC flexible. If the error persists, perform a factory reset and re-download.
Event ID: 50000: Configuration error. The loaded project contains settings incompatible with this panel type or firmware version.
Verify the project was configured for the OP 77A panel type in WinCC flexible. Update panel firmware if necessary and re-download the project.
Event ID: 60000: Firmware update error. An error occurred during a firmware update procedure.
Restart the firmware update process. Ensure stable power supply during update and use the correct firmware version for the OP 77A.
Event ID: 70000: Watchdog timeout. The panel's internal watchdog has triggered due to a system hang or software fault.
Cycle power to the panel. If the fault recurs frequently, re-download the project and check for excessive tag polling loads in the configuration.

Frequently Asked Questions

What communication protocols does the OP 77A (6AV6355-1AA31-8DL6) support?

The OP 77A supports MPI and PROFIBUS DP communication protocols, allowing direct connection to SIMATIC S7-200, S7-300, and S7-400 PLCs.

What software is required to configure the OP 77A?

The OP 77A is configured using Siemens WinCC flexible 2005 or a later compatible version. Projects are downloaded to the panel via a PC adapter cable.

What is the supply voltage for the 6AV6355-1AA31-8DL6?

The panel operates on a 24 V DC supply voltage, which is standard for SIMATIC HMI operator panels.

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

The OP 77A provides IP65 protection on the front face when correctly installed in a panel cutout, making it suitable for environments with dust and water spray.

Can the OP 77A be used with an S7-1200 or S7-1500 PLC?

The OP 77A is not natively supported for direct communication with S7-1200 or S7-1500 PLCs, as these controllers use newer communication protocols. It is designed for use with S7-200, S7-300, and S7-400 series controllers.

Troubleshooting

Display remains blank after power is applied

Check that 24 V DC is present at the power supply terminals of the panel. Measure voltage at the connector to confirm supply integrity. Inspect for any blown internal fuse.

Ensure the 24 V DC supply is within tolerance. Replace any blown fuse with the correct rating. If supply is confirmed good and display remains blank, the internal power supply board or LCD may require replacement.

Panel displays communication error and cannot connect to PLC

Verify the MPI or PROFIBUS DP cable is correctly connected and terminated at both ends. Check that the PLC address in the panel project matches the physical PLC address setting.

Replace or reseat the communication cable. Correct the station address in WinCC flexible and re-download the project. Ensure termination resistors are enabled only at the two physical ends of the bus.

Project download fails or transfer cannot be initiated

Confirm the panel is set to transfer mode before starting the download from WinCC flexible. Check the PC adapter cable connection between the PC and the panel's MPI port.

Place the panel in transfer mode via the start screen menu. Use a compatible Siemens PC adapter (USB or RS-232). Retry the download. If failure persists, perform a panel reset and attempt again.

Function keys do not respond to presses

Inspect the membrane keypad for physical damage, contamination, or deformation. Test each key in a diagnostic screen if available in the project.

Clean the keypad surface. If individual keys are non-functional due to membrane damage, the keypad membrane assembly should be replaced. Contact a repair specialist for membrane replacement.

Panel repeatedly restarts or watchdog resets occur

Check the 24 V DC supply for voltage dips or instability under load. Review the project configuration for excessive tag update rates or communication polling loads.

Stabilize the power supply, ensuring it can deliver sufficient current. Reduce tag polling frequency in WinCC flexible. Re-download the project. If restarts continue, the panel may require servicing of its internal CPU board.

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