A Somab Transmab 400 with a NUM 750 control and Sauter driven-tool turret displayed a turret coincidence alarm whenever MDI or automatic mode was selected. Axis motion, reference return, and tailstock movement remained available, but every tool call failed and the turret contactor did not energize. The reported turret was type 0.5.473.516.
Identify the turret state
First determine whether the turret is locked at a tool station or stopped between stations. If it is between stations, the controller may not receive a valid position code. Transport was the suspected cause in this case because the turret may have moved while the machine was braced.
In MDI, reset the control and request a tool different from the current tool with M6 T1, substituting an appropriate tool number. If the turret does not rotate and its contactor never energizes, investigate the turret-evolution permissive before treating the fault as a rotation motor problem.
Restore turret evolution with M122
The machine documentation identified M122 as the turret-evolution command. Executing it caused the turret to make one complete revolution and then index into position. Subsequent tool changes selected the correct stations without the coincidence alarm.
- Confirm that the turret and machine are clear for rotation.
- Enter
M122using the machine's documented command procedure. - Allow the turret to complete its full revolution and settle at a valid station.
- Request several different tools in MDI and confirm that each commanded station is selected correctly.
Check position feedback if M122 does not recover it
The turret position is encoder-based and represented by a 7-bit code plus a strobe signal. With the turret locked at a station, compare the active position code against the turret documentation. Trace the strobe and position-bit signals through the electrical drawings, then inspect them either on an input card equipped with indicators or through the control's PLC memory display.
| Observed behavior | Checks supported by the evidence |
|---|---|
| Rotates beyond one revolution without locating the station | Check the indexing solenoid, its command relay, the encoder, and the NUM input card. |
| Does not rotate | Check the rotation-motor command and the mechanical drive. If the contactor never energizes, verify the evolution permissive first. |
| Locked at a station but coincidence remains | Validate the 7-bit encoder code and strobe at the PLC inputs. |
| Stopped between stations | Restore a valid position using the applicable turret documentation. |
Verify the driven-tool disengagement permissive
This turret design uses two sensors to report engagement and disengagement of the driven-tool coupling. The coupling must indicate disengaged before the control grants permission for turret evolution. If M122 produces no movement, check both sensor states and their PLC inputs before replacing the encoder or input card.
Documentation for turret 0.5.473.520 was used as a related reference for the installed 0.5.473.516. The evidence states that their turret size differs while their mechanics and control are the same, but confirm signal assignments against the machine electrical drawings before testing inputs.
FAQ
How do I clear a turret coincidence alarm on a NUM 750?
On the reported Somab Transmab 400, the documented M122 turret-evolution command made the turret complete one revolution and recover a valid station. Verify recovery by commanding several tool changes in MDI.
Why does a Sauter turret ignore every M6 tool call?
If no rotation contactor energizes, verify the turret-evolution permissive. The driven-tool coupling must report disengaged through its two sensors before turret movement is authorized.
What feedback should I check for a turret coincidence fault?
Check the encoder's 7-bit position code and strobe signal at the NUM PLC inputs. Compare the active code with the turret position table and use the electrical drawings to identify each input.