A Daewoo DMV 2040 with a Fanuc 21i control displayed a blinking RMT DGN indication and the detailed message RS 232C Error (5). Jogging, unclamping, and other manual functions worked, but Cycle Start in MEM mode, MDI execution, and spindle rotation did not. The available evidence points to an unresolved remote-diagnostic or serial-interface fault, not a confirmed lubrication, axis-position, door, or NC-alarm problem.
Separate Confirmed Symptoms From Suspected Causes
| Observation | Engineering interpretation |
|---|---|
| Blinking RMT DGN | The indication is associated with remote diagnostics in the supplied evidence. |
| RS 232C Error (5) | The control reports a serial-interface error; the evidence does not define the code's exact internal cause. |
| Manual operations work | The machine is not completely inoperative, but this does not prove that all run permissives are satisfied. |
| MEM Cycle Start, MDI execution, and spindle rotation fail | The fault coincides with blocked automatic and commanded operation. The evidence does not establish whether the serial error directly causes every blocked function. |
| RS-232 hardware position appears empty | A removed connector, card, cable, or channel is a plausible hypothesis because the control may still be configured to use missing hardware. |
| I/O channels 0 through 4 were tried without effect | Changing the channel alone did not clear the reported condition. |
Check the Missing Interface Before Changing More Settings
The strongest physical clue is the empty opening where the operator expected a 21-pin plug. Inspect the control and cabinet documentation for a removed or disconnected serial or remote-diagnostic component. Check for loose internal plugs, disconnected wiring, an absent interface card, and machine-builder modifications. Treat these as hypotheses until the installed hardware and electrical documentation confirm the original configuration.
Do not assume the empty opening is the only fault. The operator reported checking oil, the NC alarm indication, axis zero position, and door security, but those observations do not identify every permissive used by the machine builder.
Evaluate the I/O Channel Evidence
The supplied evidence identifies channels 0 and 1 with RS-232 and channel 4 with PCMCIA. The operator tried channels 0, 1, 2, 3, and 4 without clearing the error, so repeating channel selection is unlikely to isolate the fault without first determining which physical interface the machine configuration expects.
- Record the current I/O channel and any related configuration before making another change.
- Identify the installed or missing interface from the machine drawings, control hardware, and configuration records.
- Select only the channel that matches the verified physical interface.
- If the control displays must turn off power, follow the machine's approved shutdown and restart procedure; the evidence does not support power cycling after every channel change.
Verify Recovery and Escalate With Specific Evidence
After correcting a confirmed hardware disconnection or configuration mismatch, verify that RS 232C Error (5) and the blinking RMT DGN indication clear. Then recheck MDI execution, MEM Cycle Start, and spindle commands under the machine's normal safety procedure. If the error remains, provide the machine model, control model, exact message, selected I/O channel, photographs of the empty interface opening, and the results of the connector and card inspection to the machine builder or Fanuc support.
The evidence does not supply the parameter that enables remote diagnostics, the definition of Error (5), or a supported method for disabling the missing interface. Do not guess a parameter number or bypass the alarm without model-specific documentation.
FAQ
What does Fanuc 21i RS 232C Error (5) mean?
The evidence confirms a serial-interface error associated with a blinking RMT DGN indication, but it does not provide the code's exact definition. Check for missing or disconnected interface hardware and obtain the model-specific alarm documentation.
Which Fanuc I/O channels should I check for RS-232?
The supplied evidence associates channels 0 and 1 with RS-232 and channel 4 with PCMCIA. On this machine, trying channels 0 through 4 did not clear the error, so verify the installed interface before changing the selection again.
Can I disable RS-232 to clear RMT DGN on a Fanuc 21i?
No supported disable parameter is present in the evidence. Identify the missing connector, card, or wiring and use the Daewoo DMV 2040 and Fanuc 21i documentation or official support before changing parameters or bypassing the alarm.