Sinumerik 850M Recovery: TC630 NC/PLC MD, Spindle, Magazine Reset

Problem Overview

A Fritz Werner TC630 horizontal machining center (machine serial 816480) equipped with a Siemens Sinumerik 850M CNC and a SIMATIC S5-150U PLC has been put into commissioning without an original machine data backup. The commissioning engineer has loaded the NC machine data (NC MD) and the PLC machine data (PLC MD) from one of six sister machines in the same shop (mixed Sinumerik 850 and 880 fleet) and confirmed that the X, Y and Z linear axes successfully reach their reference marks. Two anomalies remain and they are the focus of this recovery procedure:

1. The automatic tool magazine does not index, rotate, or respond to M-codes that call a tool change.
2. The main spindle does not rotate when commanded from the handwheel (JOG mode, spindle handwheel override).

The PLC program itself is preserved on EEPROM, so the S5-150U user program does not need to be re-authored. The problem is parametric: NC MD and PLC MD from a sister machine do not match this specific TC630 because the TC630 has an additional input rack and a slightly different machine number/serial-dependent identifier. Reference of the linear axes is the easiest possible acceptance test - it only confirms that the axis encoders, the SIMODRIVE 610 power sections, and the reference-point cam logic are alive. Magazine indexing and handwheel spindle control depend on parameters that the operator panel exposes only after the tool-changer M-codes and the spindle override path are correctly defined, which is the actual gap left by the missing backup.

System Architecture: TC630, 850M, S5-150U, SIMODRIVE 610/650

Understanding the data and signal flow between the four major subsystems is the first step in any recovery. The Fritz Werner TC630 is a 1980s-era horizontal machining center with chain or drum-type tool magazine, hydrostatic or ballscrew feed drives, and an AC main spindle. The original Siemens drive complement on this generation of machine is almost always:

• Feed axes X, Y, Z: SIMODRIVE 610 analog three-phase modular drive, set-point from the 850M via +/- 10 V on a 6SC6101/6SC6102 module pair. Drives feed 1FT/1FK feed motors with resolver feedback (8FX or 9FX series resolvers are most common).
• Spindle: SIMODRIVE 650 digital spindle drive, set-point from the 850M over a serial link or +/- 10 V analog with a 6SN1122 power section, driving a 1PH or 1PM spindle motor with built-on encoder.
• NC: Sinumerik 850M with operator panel (OP 320 or 6FC3 803-... keyboard), MMC/CPU modules, NCK memory (battery-backed SRAM or EEPROM PCMCIA card), and the HMI loader disk.
• PLC: SIMATIC S5-150U central controller (CPU 928 or 928B), with input/output cards on a 6ES5 153 interface, and the user program on EPROM/EEPROM modules plugged into the S5 rack.
• Communication: NC-PLC coupling via a parallel dual-port RAM and discrete I/O; I/O backplane is the S5-150U I/O bus. Field I/O is 24 V DC on input cards and 24 V DC / relay output cards.

The recovery problem reduces to making every block of data in this picture agree: the NC MD must match the actual feed motors, ballscrew pitches, reference-cam geometry, and tool-pockets on this serial-number-816480 machine, while the PLC MD must drive the S5-150U through the exact M-codes, T-codes, and tool-table entries that this NC MD expects. A wrong number in any single cell propagates to the symptoms you are seeing.

Why the Recovery Is Difficult Without an Original Backup

Sinumerik 850M and 880 controls were introduced in the late 1980s and were taken out of series production around 1998. The NCK memory on a 850M is small by modern standards: the working memory of the standard 850M is in the 256 KB to 1 MB range, backed by battery-backed SRAM or by an EEPROM PCMCIA card. Modern CAD/CAM programs are routinely tens to hundreds of megabytes in G-code size, so the 850M cannot run the typical CAM program of today; it can only run the smaller hand-written or post-processed programs that fit its NC memory.

Three structural facts make a no-backup recovery fundamentally harder than a typical service job:

1. The NC MD is partially derived from the machine's mechanical build, not from a generic TC630 template. Ballscrew pitch, encoder line count, axis acceleration limits, jerk filter coefficients, and the software limit switch positions all reflect the specific machine tool on the shop floor, not the catalog brochure. Sister machines share enough to drive the axes, but magazine pocket count, magazine pitch on the chain, and the home-pocket position are usually machine-specific.
2. The PLC MD is half parameter, half program. STEP 5 blocks (OB 1, OB 21/22, PB 30-39 for axes, PB 40-49 for spindle, PB 70-79 for magazine, plus FB and DB blocks) contain the tool-change sequence, magazine rotation direction, and the interlock with the spindle orientation. The machine EEPROM preserves the program, but the matching parameter block (DB 60-69 typically) is NC-driven and may differ from sister-machine data because of different magazine geometry.
3. Spindle handwheel control is NC-MD-driven, not PLC-driven. Whether the handwheel is allowed to command the spindle at all is set by a bit in NC MD (typically MD 5400 series in the 850M spindle parameter group). Sister-machine data may have this bit disabled, which is exactly the symptom observed: spindle does not respond to the handwheel.

Initial Diagnostics Before Touching Parameters

Before any parameter is changed, validate the hardware chain. Many 850M "parameter" problems are actually worn sensors, broken cables, or aged battery cells. Run the following sequence first:

1. Battery check. On the S5-150U, the lithium battery on the CPU 928/928B and on the 850M NCK backplane must be replaced if the system has been de-energized for more than a few weeks. A dead battery silently clears the NC MD on next power-down. Confirm date codes; replace with a fresh 3.6 V lithium (Siemens 6ES5 980-0AA11 or 6FC3 947-1AA10 type, depending on slot).
2. EEPROM/EPROM presence. Open the S5-150U central rack and confirm that the EPROM modules are firmly seated. With the EEPROM intact, the PLC program is preserved. Note the part number on the EPROM label; this is your program version stamp.
3. Operator panel test. On the 850M, enter diagnostics by pressing the SETUP key and the password "EVENING" (the standard service password on 850/880 controls) or whatever shop-specific password has been set. Verify the HMI version, NCK version, and PLC version. The PLC version string on a 850M should match the STEP 5 program you have in the EEPROM.
4. Reference-cam check. All three axes reference - so the cam, encoder, and drive loop are working. Capture the actual reference-point offset values (NC MD 2408 and 3408 family). They are machine-specific and will be used to tune the cross-load.
5. Spindle handwheel wiring. Trace the handwheel pulses from the operator panel to the 850M NCK handwheel input. On 850M, the handwheel is usually a 100-pulse-per-revolution unit with two channels. Use an oscilloscope on the input card; you should see clean quadrature. If you see nothing, the symptom is wiring, not parameters.
6. Magazine proximity sensors. The chain/drum magazine on a TC630 typically has 24, 30, 36, or 40 pockets. Verify that the home-pocket proximity switch and the count-proximity switch are working. The PLC needs both to count pockets. A failed switch will lock the magazine even if the parameters are correct.

NC MD Restoration Procedure

The NC MD on Sinumerik 850M is grouped into functional blocks. The sister-machine backup gives you a complete copy, but you must audit the groups listed below before applying it. Use the 850M menu path: SETUP -> NC MD and step through each group. Where a value must be re-derived for serial 816480 specifically, mark it with a marker pen on the printed parameter list.

Save the NC MD via the HMI menu to a serial line printer or, if available, to a PC running the SinuCom commissioning software over RS-232. The save format is a plain-text .TXT parameter file; archive both the sister-machine version and the audited 816480 version with date stamps.

PLC MD Restoration Procedure

The PLC MD in the 850M/S5-150U pairing is the data block layer that the S5 program reads at runtime. STEP 5 syntax is statement list (STL) or ladder (KOP). The key data blocks for magazine and spindle behavior are typically:

• DB 60 - Magazine parameters (pocket count, rotation direction, dwell time, max search time).
• DB 61 - Tool table mirror (T1..T40 with magazine pocket assignment).
• DB 70 - Spindle parameters (gear-stage select, orientation angle, handwheel enable).
• DB 80 - General machine status, feed/spindle enable flags.

Read these data blocks from the running sister machine via STEP 5 online:

STEP 5 -> Online -> Set PG/PC interface -> COM (TTY, 9600 8E1)
STEP 5 -> File -> Open -> /PATH/TO/SISTER.S5D
STEP 5 -> Test -> Data View
STEP 5 -> Select DB 60 -> Read

Save the output. Now edit DB 60, DB 61, DB 70 to match the TC630. Common edits are pocket count, home pocket, and the magazine rotation CW/CCW bit. Use the STEP 5 editor on a PG 720/740/755 (or a PC with the Siemens STEP 5 V7.x package running in a Windows XP/7 virtual machine) to overwrite the data block, then write the modified DB back to the running PLC over the online port.

Tool Magazine Recovery (the Unique Failure)

The tool magazine on a TC630 is the most difficult subsystem to recover without a backup. The typical magazine path on a 850M-controlled machine is:

1. Spindle orient (M19) to put the drawbar in the correct window.
2. A-axis or Z-axis to the tool-change position.
3. Magazine arm extended (or chain indexed) to the target pocket.
4. Tool unclamped, arm withdraws old tool and inserts new tool, or chain rotates to deliver new tool.
5. Spindle clamp, magazine arm retract, axes return to program path.

Each step has corresponding NC MD, PLC MD, and physical-sensor requirements. For the 816480 machine, the failure to index is almost certainly a combination of:

• NC MD 6xxx (magazine) does not match the physical pocket count. If MD 6000 says 30 and the actual chain has 24 pockets, the count-pulse decoder in the PLC will never reach the requested target. The PLC will time out and post a magazine error.
• PLC MD DB 60 has the home pocket set to a value that does not exist on this chain. The home search (often invoked by M70 on 850M, or automatically on first tool change after power-up) drives the chain to the home proximity switch, then sets the count to the MD 6001 value. If MD 6001 is wrong, every subsequent search is offset by a constant.
• One of the magazine I/O signals is wired to the wrong input byte. Sister machines differ in their I/O address map because the 816480 has an additional input rack. The home-pocket signal may be wired to a different byte than the sister machine assumed. Re-trace the magazine I/O with a multimeter and update the STEP 5 PB 70 block (or whichever PB contains the magazine I/O mapping) to match.

To confirm which sub-block is at fault, force a known state from STEP 5 online:

STEP 5 -> Test -> Variable -> Force
Force DB60.DBX 0.0  = 1       ; Magazine enable
Force DB60.DBW 2   = 24      ; Pocket count = 24 (actual count)
Force DB60.DBW 4   = 1       ; Home pocket = 1
Force M 70.0       = 1       ; Trigger home search

Watch the chain physically. If it rotates to the home switch, stops, and the PLC sets the ready flag, you have proven the parameter side. If it does not, the issue is a sensor, a contactor, or a PB block. Move your debugging to the I/O at that point.

Spindle Handwheel Restoration

The spindle handwheel on a 850M is the front-panel knob that allows the operator to manually advance the spindle (rotate it) without running a program. It is invaluable for setup and for inching into a part. There are three independent gates that must all be open for it to work:

1. Hardware gate. The handwheel pulses must reach the 850M NCK. Check at the connector backshell. Confirm 24 V on the supply pin, then scope the two signal channels (A and A\) for clean quadrature with at least 2 V swing.
2. PLC gate. The PLC must report "spindle handwheel enabled" to the NC. This is typically a flag in the NC-PLC interface area, set by PB 50 (handwheel logic) and confirmed in DB 80. Force it ON from STEP 5 to bypass during commissioning, but the proper fix is to find why the PLC is not setting it - usually a missing mode-select key (JOG mode, spindle-override axis) or a missing drive enable.
3. NC MD gate. The 850M has a dedicated MD that enables spindle handwheel as a separate axis. On 850M, look in MD 5400-5499 for "Spindle handwheel enable" or "Spindle as positioning axis in JOG". The sister machine had this bit OFF, which is why the 816480 also has it OFF after cross-load. Set the bit, save, and power-cycle the NC.

SETUP -> NC MD -> 5400
MD 5400.0 = 1     ; Spindle handwheel enable
MD 5400.1 = 0     ; Spindle follow-up enable (for live tool: 1)
MD 5410   = 5     ; Spindle handwheel increment, degrees per detent
MD 5420   = 110   ; Spindle handwheel max override %

After saving, run a controlled test: select JOG, choose spindle as the active axis on the handwheel selector, set override to 10%, and turn the handwheel. The spindle should rotate at a small percentage of its rated RPM. If it does not, use the NC diagnostics screen (DIAG) to see whether the NC is receiving the pulse and whether the spindle is in follow-up mode. A common second-order issue is that the spindle encoder feedback is open; without encoder feedback, the NC refuses to command the spindle in JOG mode.

STEP 5 Online Diagnostics Procedure

STEP 5 is the only tool that lets you read the S5-150U program, modify DBs online, and watch the I/O. The recommended software stack is STEP 5 V7.23 (or later) running in a Windows 7 32-bit VM with a COM port assigned to the Siemens PC-TTY adapter (6ES5 734-1... series) or to a USB-to-RS232 adapter with the correct 15-pin D-sub wiring.

1. Connect the PG/PC COM port to the S5-150U online port (X4 on the CPU 928B).
2. Set the COM port to 9600 baud, 8 data bits, even parity, 1 stop bit, with protocol "AS511".
3. In STEP 5, choose Online -> Connect. The status bar should change from "Offline" to "Online".
4. Open the program file. If the EEPROM is intact, the program read from the CPU should match the EEPROM dump byte-for-byte.
5. Open the I/O test. Confirm that toggling a 24 V input on the panel changes the corresponding flag in the I/O image.
6. Open the status display for PB 70 (magazine) and PB 50 (handwheel). Watch the flags change as you press the JOG keys and the magazine home button.

Modernization Alternatives: 840D sl and 840C

If the recovery work drags on, the most realistic long-term path is a CNC retrofit. The two options in the Siemens family that preserve the existing drives and motors are:

The 840D sl is the supported path at Siemens. The NCU 710.3B PN with a SINAMICS S120 line module and 611-D-compatible interface cards is the closest drop-in for an existing 610/650 cabinet. Siemens Industry Online Support has application notes for "Drive migration 6SC6 -> SINAMICS" that walk through the terminal strip wiring. Programming uses SinuTrain and the Create MyConfig tool to size the NCU and the line module.

Spare Parts and Long-Term Viability

The 850M is past the end of series production. Spare parts come from three pools: Siemens factory service (declining), independent stockists, and pulled parts from decommissioned machines. Critical spares to have on the shelf for a fleet of six similar machines include:

• CPU 928B (6ES5 928-3UB12 or 3UB21) - long lead time from stockists.
• NCK memory cards (6FC3 303-...) and lithium batteries.
• SIMODRIVE 610 power modules (6SC6101, 6SC6102) and 650 modules (6SN1122).
• 1FT/1FK feed motors of the specific frame size used in the TC630 (verify frame size and stack length).
• Operator panel keypad membranes (6FC3 803-...) - the rubber wears out and is no longer stocked new.

Verification and Final Commissioning

Run the following acceptance matrix on the recovered 816480. Every cell must pass before the machine is released to production.

Document every parameter change in a recovery log (date, parameter number, old value, new value, reason, engineer). This log becomes the new backup for the next time this machine loses its data.

FAQ