SINUMERIK 810G/820G %PCA Alarm Text Upload and Download Procedure

Overview

The SINUMERIK 810G and SINUMERIK 820G are compact 3-axis CNC controllers from Siemens widely deployed on milling, drilling, and turning retrofits. Both controllers support a per-channel alarm text file identified as %PCA (sometimes referred to as the message or alarm text file). Operators and commissioning engineers routinely need to back up this file before machine upgrades, edit alarm text in a PC-based ASCII editor to add local-language messages, and re-download the modified file to the controller's NCK (Numerical Control Kernel) memory.

This procedure uses the standard Siemens DNC tool, PCIN or its Windows successor WINPCIN, over a V.24 (RS-232C) serial link. The same procedure applies to GA1, GA2, and GA3 software versions, but the message-file output capability is only guaranteed on the GA3 release per the original Siemens service documentation for the 810G/820G platform. The official installation manual is hosted on the Siemens Industry Online Support portal as document 6FC5297-2AD10-0BP0 (Installation Instructions GA3, 339_810G_820G_GA3) at SINUMERIK 810G/820G GA3 Installation Instructions (PDF).

System Identification and %PCA Availability

Before any data transfer is attempted, confirm the controller variant because the %PCA upload/download workflow depends on the installed software version. Use the controller's startup screen or the diagnosis page to read the version string.

Prerequisites

1. PC with serial port (COM1 or COM2) or USB-to-RS232 adapter. Native COM ports are strongly preferred; many USB adapters introduce timing jitter that corrupts V.24 transfers at 4800 baud.
2. PCIN (DOS) or WINPCIN (Windows 3.1/95/98/2000 compatible). WINPCIN versions 3.x or higher are recommended. The binary can typically be supplied with the controller's installation disc or downloaded from Siemens Industry Online Support under the SINUMERIK 810/820 documentation set.
3. V.24 (RS-232C) cable, shielded, 1:1 pinned (no crossover), with shield bonded at the PC end only. Length should not exceed 15 m for reliable 4800 baud operation.
4. ASCII text editor capable of LF or CRLF line endings (Notepad++, UltraEdit, or similar). The %PCA file uses a Siemens-specific record structure with fixed-width fields; do not use a word processor that introduces formatting characters.
5. Password / access level to enter the controller's Setup and to write machine data 5011/5013. Manufacturer password 1111 or the customer password is required.

Communication Interface Configuration

The SINUMERIK 810G/820G uses a 25-pin female Sub-D connector on the controller side labeled X121 for the V.24 interface. Configure both the PC software and the controller machine data to the same parameters; mismatched parameters are the single most common cause of garbled text or aborted transfers.

Required PC-side protocol parameters (PCIN/WINPCIN)

Controller-side machine data (MD 5011 and MD 5013)

The serial interface on the 810G/820G is controlled by machine data words 5011 and 5013. Each MD is an 8-bit value where individual bits select interface behavior. Per the field-proven configuration, both words are set to the binary mask 11000110.

Bit positions correspond to the standard Siemens 810G/820G bit numbering convention (bit 0 = LSB, bit 7 = MSB). The combined bit pattern selects the V.24 protocol framing matching the PC-side settings above (4800 baud, 7 data bits, 2 stop bits, even parity). When entering values on the controller, type the decimal equivalent 198 or use the binary editor within the Setup screen.

Hardware Connection

1. Power off the SINUMERIK 810G/820G controller. Power off the PC.
2. Connect the V.24 cable between the controller's X121 25-pin connector and the PC's COM1 (9-pin) or COM2 port using a 25-to-9 pin adapter if required.
3. Verify the shield is bonded to the connector shell at the PC end only, leaving the controller end floating to avoid ground loops.
4. Power on the controller and wait for the ready state. Power on the PC and launch WINPCIN.

Uploading the %PCA File

1. On the controller, navigate to Setup > Data I/O > RS-232 and confirm the V.24 settings match those in the table above.
2. Select the file to be transmitted. From the file directory view, choose %PCA (alarm text) and mark it for output.
3. On the PC, in WINPCIN, select Receive Data and confirm the protocol parameters (4800, 7, 2, E). The display-on and directory-on flags will be visible in the WINPCIN status bar.
4. Initiate the transfer from the controller (typically NC Start or the Output soft key in the data I/O menu).
5. Watch the WINPCIN transfer window. A successful transfer of %PCA typically completes in 10-30 seconds. The file is saved in the WINPCIN working directory with a default name (e.g., PCA.000 or N00000.PCA).
6. Open the saved file in a binary-safe ASCII editor. Do not re-save the file in any other format. Verify the file begins with the standard %PCA header and contains fixed-width alarm text records.

Editing the %PCA Alarm Text

The %PCA file is a structured text file. Each alarm record occupies a fixed number of columns and has a defined layout. Editing rules:

• Preserve column positions for all numeric fields (alarm number, bit mask, PLC address references).
• Alarm text may be in any language using 7-bit ASCII characters. Avoid tabs, control characters, or characters above 0x7F unless the controller's character set is confirmed to support them.
• Do not alter record count or record order. Adding a new alarm requires inserting a new record at the end of the existing sequence and updating any associated index structures; this is a job for a trained commissioning engineer, not a routine text edit.
• Save the file with LF line endings (or the line ending used by the original upload) and keep the file name unchanged.

Downloading the Modified %PCA File

1. On the controller, place the NCK in the appropriate state for data input (typically Setup > Data I/O > RS-232 > Input).
2. On the PC, in WINPCIN, select Send Data and choose the modified %PCA file. Verify the protocol parameters match.
3. Initiate the transfer from the PC.
4. The controller displays the incoming file in its directory view and asks for confirmation to overwrite. Confirm Yes.
5. Wait for the transfer to complete. The controller reports Transfer OK or equivalent message in the status line.
6. Exit the data I/O menu and reset the alarm history if required to force display of modified text.

Verification

After download, confirm the modified alarm text is active. Use one of the following methods.

1. Trigger a known alarm. Cause a controlled condition that raises an alarm whose text was modified (e.g., traverse limit, low lube pressure, spindle speed out of range). Verify the displayed text matches the modified version exactly, including line breaks if any.
2. Re-upload the %PCA file immediately after download. Compare the re-uploaded file byte-for-byte with the downloaded file using a checksum tool (FCIV on Windows, md5sum on Linux). Identical checksums confirm round-trip integrity.
3. View the alarm log on the controller. The log should display the new text strings for both cleared and active alarms.
4. Power-cycle the controller and confirm the modified text persists. The %PCA file is stored in battery-backed NCK memory; modifications should survive a normal power cycle.

GA3-Specific Considerations

The GA3 software version is the first variant of the 810G/820G family that fully supports output of the message file (%PCA) over the V.24 interface. Earlier variants (GA1, GA2) hold alarm text in a different memory structure that is not directly accessible through PCIN/WINPCIN. If a non-GA3 controller is in service, the equivalent procedure is:

• Use the Siemens Programming and Setup Tool (PST) or the controller's text editor screen to view and modify PLC alarm text directly on the HMI.
• For machine-specific alarm strings, edit the relevant FB (function block) text constants in the PLC program using the Siemens S5 programming tools, not the %PCA transfer procedure.

On GA3 controllers, the %PCA file may initially be in initial-clear state, meaning it exists in the NCK directory but contains only default Siemens alarm text. In that case, the upload succeeds but returns a default file; the editing procedure above then becomes a "modify and download" cycle, not a true backup-and-restore cycle.

Troubleshooting Matrix

Field-Proven Cautions

• Always perform the %PCA transfer on a stable power supply. A brown-out during write can corrupt the NCK battery-backed memory and force a full initial-clear recovery.
• Keep a printed copy of MD 5011 and MD 5013 values taped to the inside of the controller cabinet. If the values are ever lost, the controller can be reconfigured without external documentation.
• WINPCIN is legacy software. On modern Windows (10/11) it may not detect USB-to-serial adapters reliably. A dedicated legacy laptop with a native RS-232 port is the most reliable platform for these transfers.
• Document the date, software version, and operator of every %PCA change. Machine builders and integrators may need to roll back to a known-good alarm text set when a downstream PLC program is changed.

Frequently Asked Questions