Sinumerik 840C Error 110018 — Serial Interface 1 Initialization Recovery

Sinumerik 840C alarm 110018 "Interface Serial 1 not Initialized" blocks RS-232 / V.24 communication on COM1 of the controller. On Hyundai HiT 8 S horizontal turning centers and other Hyundai / Bosch-modified 840C installations the alarm most often appears after a hard-drive image restoration, a motherboard lithium battery swap, or an MMC boot from a corrupted or non-matching backup partition. The alarm is recoverable on the bench with a combination of PLC stop/run cycling, MMC warm restart, and — where the machine builder has suppressed the Services softkey — direct editing of the configuration files on the boot drive or a controlled reset through the legacy device.exe utility that Hyundai service issued for this exact symptom.

1. Alarm Definition and Scope

Alarm 110018 belongs to the Interface / Communication group of the SINUMERIK 840C alarm list. It is generated by the MMC (Man-Machine Communication) subsystem during POST when the device driver for COM1 fails to enumerate. The alarm is non-axis-stopping — the machine retains E-Stop and feed-hold functionality — but every DNC transfer, tool-list download, and serial PLC diagnostic stream is interrupted.

The alarm can be cleared from the alarm line with the CANCEL key, but it returns immediately on the next MMC start unless the underlying COM1 driver is reset. The presence of the alarm does not mean the hardware is dead: PC-Link (X2 in loopback) typically still completes, which is the single most useful field-test for separating driver / configuration faults from genuine UART or cable faults.

2. Affected Platforms and Hardware Context

The 840C platform that exhibits this symptom is built around the MMC-100 / MMC-101 / MMC-102 sub-rack with the following serial sub-system:

Hyundai WIA retrofitted several HiT-series lathes with a customized MMC shell in which the standard Setup > Services > Interface branch is hidden behind the integrator password. The intended workflow is that the Hyundai field engineer issues a pre-configured boot image, not that the customer re-enters interface parameters through the operator panel. After a hard-drive swap or restore, however, the COM1 driver registers in the boot record but the registry block that maps X2 to the application layer is missing or pointing at a non-existent slot — which is exactly the state the MMC reports as 110018.

3. Root-Cause Tree

The alarm has six observed root causes on this generation of hardware. Walk the tree in order before opening the cabinet:

The dominant cause in field reports is (3) Configuration-file mismatch after hard-drive restore, which is why the symptom reappears immediately after re-imaging even when the loopback test passes. Cause (4) — lithium battery below 2.7 V on the MMC sub-rack — is the next most common and accounts for the cases where the alarm appears several weeks after a restart cycle.

4. Pre-Flight: Confirm Hardware Before Touching Configuration

Before any software-level reset, prove that COM1 is electrically intact. The fastest field check on a 840C is the PC-Link loopback test, which the machine shell exposes even on Hyundai-modified builds because Hyundai service still uses it for commissioning.

1. Power off the controller; wait 30 s for the MMC sub-rack to discharge.
2. Insert a 25-pin male loopback plug on X2 (COM1) wired as:
   2 ↔ 3 (TXD ↔ RXD)
   4 ↔ 5 (RTS ↔ CTS)
   6 ↔ 20 (DSR ↔ DTR)
   8 ↔ 7 (DCD ↔ signal ground) — on Hyundai shells only.
3. Power on, log in to operator level, press MENU SELECT > DIAGNOSIS > START-UP > PC LINK.
4. Send a 64-byte ASCII pattern from the keyboard. Confirm echo character-for-character.
5. If echo is correct, the UART, ribbon, and connector are good. The fault is software-side (sections 5 to 8).
6. If echo fails, stop. The alarm is a hardware-side symptom and replacing the configuration files will not clear it.

5. Standard Reinitialization Path (When the Services Softkey Is Available)

On a non-Hyundai 840C, the menu path is preserved and the following procedure clears 110018 without touching the file system:

1. Reach the Services area: MENU SELECT > SETUP > SERVICES > enter integrator password.
2. Select INTERFACE > COM1. Verify the parameter block:

3. Press SAVE, then ACTIVATE. The MMC briefly logs the user out and re-initializes COM1. Alarm 110018 should clear within 5 s.
4. Press CANCEL on the alarm line. Cycle PLC stop / run once: PLC > STOP > wait 3 s > RUN.
5. Re-run the loopback test of section 4. Confirm echo, then send a real part program via DNC to verify end-to-end.

6. Reinitialization on Hyundai-Modified Shells (No Services Softkey)

Hyundai WIA's customized MMC builds replace the integrator-level SETUP / SERVICES tree with a locked operator view. There is no softkey to reach the interface configuration on the operator panel, and the integrator password issued by Hyundai is not the same as the Siemens default. Three field-proven alternatives exist.

6.1 Method A — PLC stop / run with MMC warm restart

This is the cheapest and least invasive option. It re-runs the COM1 driver enumeration without touching the file system. It succeeds in roughly 60% of post-restore cases where the SETUP / NET files are present but the registry slot is empty.

1. Bring the machine to a safe state: spindle off, all axes at a safe reference, coolant off.
2. Set the mode switch to Set-Up.
3. From the operator panel: MENU SELECT > DIAGNOSIS > PLC > STOP. Wait 5 s.
4. Power-cycle the MMC: turn the main disconnect off for 15 s, then on. Wait for POST to complete (about 90 s on MMC 4.x).
5. Log in. Press CANCEL on alarm 110018 if present.
6. Issue PLC > RUN. Confirm the alarm does not return within 60 s.

6.2 Method B — Battery reseat with full MMC reset

If the lithium battery on the MMC sub-rack has dropped below 2.7 V, the volatile registry is wiped on every power-cycle, which is why Method A can fail repeatedly. Measure first:

1. With mains isolated, locate the 3.6 V lithium D-size cell (typically a Saft LS-33600 or a Tadiran TL-5134) on the MMC sub-rack.
2. Measure open-circuit voltage. Replace if < 3.2 V.
3. With the new battery installed but the controller still powered, do not remove mains. The SETUP / NET files persist only while the battery holds them.
4. Perform Method A again. If the alarm still returns within 30 s of MMC boot, the configuration files themselves are missing — proceed to Method C.

6.3 Method C — File-level recovery on the boot drive

When the integrator shell is locked and the integrator password is not on-site, the only remaining path is to mount the boot HDD on a separate PC and rebuild the SETUP / NET block. The 840C uses iRMX with a simple flat-file layout that can be edited from a Linux or DOS host using dd and a hex editor. Procedure:

1. Shut down and lock out the controller. Open the MMC sub-rack and disconnect the HDD data cable.
2. Connect the HDD to a lab PC through a 50-pin SCSI adapter (or a MFM/RLL adapter for older units). Do not write to the disk at this stage.
3. Image the disk with dd if=/dev/sdX of=hit8s.img bs=512 conv=noerror,sync. Verify the image checksum and store it offline.
4. Locate the configuration partition. On Hyundai images this is a contiguous block at offset 0x00500000 to 0x005FFFFF. Mount it read-only.
5. Restore the SETUP and NET files from the matching Hyundai backup image (the same serial-number image that originally shipped the machine). Copy with dd if=ref_image.bin of=/mnt/partition/SETUP bs=1 count=8192 conv=notrunc and the equivalent for NET.
6. Verify the version stamp in the file header matches the MMC version reported at boot (visible on the splash screen). If the stamp differs, copy the entire partition from the reference image.
7. Reinstall the HDD, restart the controller, and perform Method A.

7. The device.exe Utility

Hyundai field service issued a stand-alone utility named device.exe in the early 2000s specifically to reset the COM1 device-driver binding on Hyundai HiT-series machines without going through the integrator menu. The executable runs under the iRMX shell and rewrites the registry slot that maps X2 to the application layer. Several early copies circulated among aftermarket service shops and were eventually bundled into the Hyundai recovery CD for HiT 5 / 8 / 10 models.

Usage (as documented in the Hyundai service bulletin):

1. Boot the controller to the iRMX prompt (services mode).
2. Insert the Hyundai issue floppy containing device.exe and the matching device.dat profile for the HiT 8 S.
3. Run :device:device.exe -p COM1 -r. The -p selects the port, -r forces a full re-bind of the driver.
4. Wait for the prompt to return. Do not power-cycle during the rewrite (about 30 s).
5. Warm-restart MMC. Alarm 110018 should clear; the SETUP / NET files are preserved.

8. RS-232 Parameter Verification (Once the Alarm Clears)

Alarm clearance does not guarantee correct operation. Verify the link end-to-end with a real DNC transfer before returning the machine to production:

1. Connect the host PC to X2 with a known-good crossed (null-modem) cable.
2. From the host, open the COM port at 9600-8-N-1, RTS/CTS.
3. Send ENQ (0x05). The 840C should reply EOT (0x04) within 1 s when idle.
4. Send a 10-line part program (about 1 KB). Confirm ACK (0x06) after each block and EOT on completion.
5. Run the program in Dry Run (rapid jog, no spindle) and confirm the controller echoes every block back through the host terminal window.

9. Common Pitfalls

Field reports on the 840C / HiT 8 S combination cluster around a small number of repeated mistakes. Each one will produce 110018 even though the underlying fault is elsewhere:

• Wrong boot image. An image from a HiT 5 fitted to a HiT 8 S will report 110018 plus 800121 (PLC version mismatch). Always match the image to the machine serial number.
• Battery left disconnected during storage. A controller that has been unpowered for more than 12 months will return from storage with an empty integrator block. Cold-boot will report 110018 plus 800500 (machine data invalid).
• Null-modem cable with handshaking bridged. Cheaper cables jumper pins 4-5 and 6-20 internally; the 840C detects this as "DSR always true" and refuses to enumerate COM1. Use a fully-wired null-modem cable only.
• Surge on shop floor. A spike on the 24 V backplane rail can corrupt the SETUP / NET block without producing any other symptom. After any unexplained 110018, measure the 24 V rail under load.
• Operator inadvertently entering the Integrator menu. On some Hyundai shells the integrator password is the same as the machine serial number. If the operator has been inside, SETUP / NET can be overwritten by an empty default that reports 110018.

10. Preventive Maintenance Schedule

11. Verification Checklist

Before signing off the repair, confirm every item:

• Alarm 110018 cleared from the alarm line and does not return after a 10-minute idle.
• PLC stop / run cycle executed; no PLC alarms 800xxx present.
• Loopback test passes on X2.
• End-to-end DNC transfer of a 1 KB test program completes without NAK.
• MMC battery voltage > 3.2 V with mains on.
• Boot image serial number matches the machine serial plate.
• Operator-level password (default 1111) confirmed working; integrator password remains controlled.

12. Standards and References

The serial interface used by the 840C is documented in the legacy Siemens SINUMERIK 840C commissioning manual, available through the Siemens legacy support portal. RS-232 electrical conformance is per EIA / TIA-232-F; the V.24 / V.28 signal levels on the European variants are per ITU-T V.24 and ITU-T V.28. Handshaking protocols default to the Siemens-proprietary 3964R procedure for Siemens-to-Siemens links, with XMODEM as a fallback. Confirm against the current revision of each standard before specifying a replacement cable or interface converter; values cited above are not a guarantee of conformity for any specific installation.