Sinumerik 810D RS232 Cable: Wiring Diagram and Data Transfer

The Siemens Sinumerik 810D control uses a front-panel RS232 (V.24) port for serial NC and PLC backup, restore, and series start-up. Building the correct null-modem cable and pairing it with the right transfer utility is the first step toward a reliable data exchange with a PC. This reference covers the cable specification, DB9 pin assignment, software selection, parameter setup, and a verified transfer sequence for backup and restore of NC and PLC data.

Overview of the Sinumerik 810D RS232 Port

The 810D operator panel front exposes a male DB9 connector (typically labelled X2 or marked with the serial icon) that implements an RS232-C / V.24 interface. The port is designed for point-to-point connection to an external PC for:

• NC series start-up (cold start with data load)
• NC data backup and restore (teaching, machine data, compensation data, work offsets)
• PLC program upload/download and cross-reference generation
• Tool and zero-point list archiving
• Drive and HMI log capture

The maximum cable length for reliable RS232 communication without line drivers is generally limited to 15 m at 19200 bit/s, and shorter lengths at higher baud rates. The 810D supports baud rates from 110 up to 19200 bit/s in most firmware revisions, with 9600 and 19200 being the practical choices for file transfer.

Prerequisites

Before assembling the cable, confirm the following parts and tools are available:

• Cable: 7-core overall shielded cable, stranded conductors, 24 AWG (0.22 mm²) or heavier, characteristic impedance near 100 Ω, outer diameter 5–8 mm. The seventh conductor is used for the cable shield drain wire or for an additional signal ground tie; the shield is bonded to the metal shell at both connectors.
• Connector at 810D end: 9-pin female D-sub (DE-9S) with metal hood and strain relief. The 810D side is male (DE-9P) and the mating connector is therefore female.
• Connector at PC end: 9-pin female D-sub (DE-9S) for most desktop PCs with a built-in COM port. If the PC only has USB, use a quality industrial USB-to-RS232 adapter based on FTDI FT232 or equivalent chipset, and verify the adapter enumerates as COM1 through COMx in Device Manager.
• Assembly tools: Soldering iron (40–60 W), 60/40 or lead-free solder, heat-shrink tubing, crimp tool if using crimp-and-insert contacts.
• Transfer software: PCIN or WinPCIN installed on the PC. HyperTerminal (Windows XP/2003), Kermit, or Tera Term can be used for interactive control but not for binary NC/PLC transfer.

DB9 RS232 Pin Reference

The DB9 (DE-9) pin numbering follows the standard EIA/TIA-574 assignment. The 810D presents a DTE, the PC presents a DTE, and the cable must cross the data and handshake lines to form a null modem.

The signal ground (pin 5) is the reference for all other voltages. RS232 levels swing from approximately +3 V to +15 V for SPACE (logic 1) and −3 V to −15 V for MARK (logic 0), with a typical driver swing of ±12 V from the UART line driver.

Null-Modem Cable Wiring

Between two DTE devices, the following crossover must be implemented. The pin numbers refer to the DB9 connector on each end of the cable.

The 7th conductor of the shielded cable carries the signal ground tie. The remaining unassigned pairs (DCD, RI) are not used by the 810D serial protocol and may be left floating, or used as additional shielding/drain conductors inside the overall braid.

Inline Wiring Diagram

Cable Assembly Procedure

1. Strip the outer jacket of the 7-core shielded cable by approximately 30 mm at each end. Fold the overall braid back over the jacket to form a pigtail drain wire, or use the dedicated drain conductor inside the cable.
2. Strip each conductor 3–4 mm and tin the bare copper with solder to prevent fraying.
3. Solder the conductors to the DE-9 male (or female, depending on the application side) crimp-solder cups in the order shown in the wiring table. Observe the standard color convention if used (red, orange, yellow, green, blue, white, black) but always verify by continuity, not by color memory.
4. Bond the shield to the connector metal shell using a solder lug or by crimping the pigtail under the cable clamp. A 360° bond is preferred over a single-point drain wire to improve EMC immunity.
5. Slide the metal hood over the cable before crimping the strain relief; the hood must mechanically clamp the cable jacket, not only the conductors.
6. Continuity test every conductor with a multimeter in continuity mode. Confirm no shorts between adjacent pins (especially 2-3, 4-5, 7-8) and confirm shield continuity from shell to shell.
7. Insulation test between any signal pin and the shield with a 500 V insulation tester. Resistance should be >10 MΩ for a good cable.

Reference Wiring for Industrial RS232

The general-purpose RS232 null-modem construction pattern used for industrial controllers (DB9 female to DB9 female) is documented in third-party industrial motion control references such as Delta Motion's RMC RS232 wiring guide. The same crossover pattern applies to the 810D: TXD-to-RXD, RTS-to-CTS, and DTR-to-DSR. Where the 810D diverges is the protocol: the 810D expects a Siemens-specific handshake using the V.24 control lines and a record-oriented file transfer protocol implemented by PCIN and WinPCIN, not a transparent serial pipe.

Software Selection for NC/PLC Transfer

For an 810D on the front RS232 port, the only safe choices for full NC/PLC archive work are PCIN or WinPCIN. Generic terminal emulators can be used for BTSS (Basic Text Serial Service) dialogue and ASCII log capture, but they cannot perform the binary *.arc archive transfers that the 810D requires for cold start data load.

Communication Parameter Setup

The 810D serial transfer requires that both sides agree on baud rate, data bits, parity, stop bits, and flow control. The 810D's defaults for the front RS232 port are:

On the 810D, set these parameters in RS232 Settings on the Services screen (or via BTSS: RS232 ON then SET COM 1 9600 EVEN 7 1 RTS). Always start with 9600 bit/s and 7-E-1 for the first successful transfer before attempting 19200 bit/s 8-N-1.

Step-by-Step: NC Backup from 810D to PC

1. Connect the null-modem cable between the 810D front RS232 port and the PC COM port (or USB-RS232 adapter). Power on the 810D; the PC should not be running the transfer utility yet.
2. On the 810D, navigate to Services > Data Transfer > RS232. Set baud rate to 9600, data bits to 8, parity to None, stop bits to 1, and flow control to RTS/CTS.
3. Select the directory on the 810D side to back up (for example, all NC and PLC areas). The 810D displays the selection as a checkbox list: NCK, PLC, TOA, ZOA, CMA, RPA, SEA, etc.
4. On the PC, launch WinPCIN. In the RS232 menu, set the COM port number (e.g., COM1), baud rate 9600, data bits 8, parity None, stop bits 1, and protocol PCIN V24.
5. In WinPCIN, choose Receive Data and select a target file name with the .arc extension (e.g., backup_810d_20240101.arc).
6. On the 810D, press the Start soft key. The 810D raises RTS/CTS, sends the file header, then streams the data records. The progress bar on the 810D HMI advances as records are acknowledged.
7. When the 810D displays Transfer complete and WinPCIN shows Records received: N, exit the transfer mode on the 810D first, then close WinPCIN.
8. Verify the file size on the PC matches the expected size (a full NC backup is typically 500 KB to 2 MB, a full NC+PLC backup 1–5 MB depending on options).

Step-by-Step: NC Restore to 810D from PC

1. Place the 810D in the correct operating mode. For a full NC series start-up, the 810D must be in Power-On Reset state (NCK in cold-start mode) with the password unlocked. For an in-place restore of NC data, the 810D can be in any mode except Commissioning.
2. On the 810D, navigate to Services > Data Transfer > RS232 and select Receive NC (or the specific area to load).
3. On the PC, start WinPCIN in Send Data mode. Select the .arc file to send.
4. Set identical communication parameters on both sides (9600, 8, N, 1, RTS/CTS).
5. Press Start on the 810D, then on WinPCIN. The 810D acknowledges each record; if a record is rejected, the 810D displays the record number in the Status line.
6. When the transfer completes, the 810D automatically processes the loaded data. A PLC restart is required if the PLC program was overwritten.

BTSS (Basic Text Serial Service) Dialogue

The 810D also accepts text commands over the same RS232 port for diagnostics and selective data dump. Examples:

RS232 ON
SET COM 1 9600 EVEN 7 1 RTS
DIR
READ NCK /_N_MPF_DIR/_N_MPF0_MPF
READ PLC /_N_CST_DIR/_N_PLIST_ST

BTSS requires 7 data bits, even parity, 1 stop bit (7-E-1). HyperTerminal or Tera Term set to those parameters can be used to interactively send BTSS commands and capture responses. WinPCIN includes a BTSS mode under the Service menu that wraps these commands for scripted use.

Verification Procedure

After a successful transfer, perform the following checks:

1. File integrity: Compare the file size of the received .arc against the bytes-transferred counter in WinPCIN. They should match exactly.
2. Record count: The number of records displayed at the end of the 810D transfer (e.g., 2000 records transferred) should equal the records-received counter in WinPCIN.
3. CRC check: PCIN and WinPCIN implement a 16-bit checksum on each record. A failure is reported as Record N rejected (CRC error). The 810D halts on the first failed record; a partial restore is rejected as a whole.
4. Data sanity check: For NC data, verify that the loaded machine data takes effect (e.g., a changed position display resolution appears in the Actual field). For PLC, verify that the new program runs by observing the RUN LED and checking a known output.
5. Cold start verification: After a full series start-up, power-cycle the 810D and confirm that all expected data (axes, drives, tools, zero offsets) is present without having to reload again.

Troubleshooting Matrix

Best Practices and Field Tips

• Always perform a verification read-back after a backup: after writing the .arc to PC, perform a comparison if the utility supports it, or at least re-load the file into a second PC and confirm the byte count and header are identical.
• Store .arc files in a versioned directory (e.g., \backups\810D\machine_07\2024-01\) with the machine serial, date, and firmware version in the filename. Without firmware version metadata, a restore into a control with a different SW release may fail PLC consistency checks.
• Keep a known-good baseline archive from the commissioning of each machine. This is the fallback in case a field modification corrupts the data set.
• Use a dedicated industrial PC or a permanently installed USB-RS232 adapter for shop floor transfers. Consumer USB adapters can be a source of intermittent failures due to aggressive power saving.
• Document the baud rate, parity, and protocol on a label attached to the cable. The next engineer who picks up the cable should not have to re-derive the parameters from a multimeter.
• Do not run the cable parallel to VFD output cables. Cross at 90° if the cable must cross a power cable run, and maintain at least 200 mm separation along parallel runs.

Field Commissioning Checklist

1. Inspect the 810D front panel connector for bent pins or contamination. Clean with isopropyl alcohol if needed.
2. Connect the null-modem cable, power on the 810D, observe the link LED if present.
3. Launch WinPCIN, set parameters, run a loopback self-test on the PC side (short pins 2 and 3 of the PC end, type into the terminal) to verify the COM port works.
4. Remove the loopback, reconnect the 810D, send a RS232 ON + DIR via BTSS to confirm bidirectional communication.
5. Perform a full NC+PLC backup. Save the file with a documented filename.
6. Perform a comparison restore onto a test 810D or the same control in a controlled cold-start to confirm the archive round-trips correctly.
7. Log the procedure, parameters, and verification results in the machine's commissioning record.

FAQ