SINUMERIK 810 (810T/810M/810G) and 840C controls from the late 1980s and 1990s hold machine data, part programs, tool offsets and the PLC program in battery-backed RAM. When the battery pack fails or a module is swapped, the control comes up empty — and Siemens support for these systems ended long ago. Backups run over the V.24 (RS-232) interface using Siemens' PCIN software or any capable terminal program; the 840C can additionally archive its own hard disk / memory contents. Here is the complete procedure.
What you need
- PC with serial port or a good USB–RS-232 adapter (FTDI), null-modem cable to the control's V.24 connector (25-pin, on the operator panel or interface module — check the builder's wiring plan).
- PCIN (Siemens' classic DOS/Windows transfer tool) or a terminal program that can capture/send text with software handshake (Cimco Edit works well).
- The interface settings from the control (below). Both ends must match exactly.
Step 1 — Set the V.24 interface parameters
- On the control, open the settings/data-in-out screen and check the V.24 device settings: typical values are 9600 baud, 7 data bits, even parity, 1 stop bit, ISO/ASCII format, with software handshake (DC1/DC3 — XON/XOFF).
- Set PCIN or your terminal software identically. If transfers abort at 9600, drop to 4800 — long shielded cables in the cabinet often force it.
- Select the correct interface (some machines have two V.24 channels; the builder usually wired only one to a connector).
Step 2 — Back up each data area (control → PC)
Start capture on the PC first, then start output on the control's data-out screen. Siemens data areas have standard identifiers — save each to its own file named accordingly:
- TEA1 — NC machine data (axis, spindle, gains, limits). The most critical file; a replacement CPU or memory module is useless without it.
- TEA2 — PLC machine data.
- SEA — setting data (operator-adjustable settings).
- TOA — tool offset data.
- ZOA — zero offsets (G54–G57 etc.).
- RPA — R-parameters (arithmetic variables used by builder cycles — often hold probe and ATC calibration values).
- Part programs — main programs (%MPF), subprograms (%SPF) and cycles. Output ALL so nothing is missed; builder cycles (L-numbers/SPF) frequently contain machine-specific logic.
- PLC program — on the 810 the PLC blocks can be punched out via V.24; on the 840C the PLC (S5-style blocks) is best archived with the Siemens PG tools (STEP 5) if available. At minimum, output the PLC machine data (TEA2) and any data blocks the builder documents.
840C only: the control has an internal hard disk (or memory card on later units) with the system and archives. Use the control's own data management / archive functions to write a complete commissioning archive, and — if the machine has the option — copy it out via V.24 or the builder's streamer/floppy interface. A worn 840C hard disk is one of the most common failures on these machines; having the archive off the machine is essential.
Check every captured file in a text editor: readable content with the correct header (e.g. %TEA1), sensible size, clean end. Fix any mismatch immediately.
Step 3 — Restore procedure (PC → control)
- Enter the machine-data password / set the protection level so machine data can be written (on 810: the commissioning switch or password per the builder's docs).
- On the data-in screen, start input; then send the file from the PC. Restore in this order: TEA1 → TEA2 → power OFF/ON (or NC reset) → PLC program/blocks → SEA → TOA → ZOA → RPA → part programs.
- After machine data loads, the control typically requests a cold restart — let it complete before loading the next area.
- Reference all axes (JOG → REF): 810/840C machines are incremental, so a reference point approach re-establishes position — the procedure is the same idea as on the newer controls in our SINUMERIK referencing guide.
- Verify soft limits, spindle speeds and tool change with a dry run before production.
Common problems
- Transfer aborts partway — handshake mismatch (set XON/XOFF both ends) or baud too high for the cable run.
- ‘Data protected’ on input — protection level/password not set; machine data will not load at operator level.
- Control boots to default data after battery change — RAM was already lost; load TEA1/TEA2 from your backup, then the rest in order.
- 840C hard disk errors at boot — failing disk. Stop, image/backup whatever still reads, and repair — continued power cycling makes it worse.
- Axes alarm after restore — measuring-system or drive machine data belongs to a different machine variant; confirm you restored this machine's own TEA1, not a sister machine's.