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Siemens SINUMERIK Controller
Communication · Intermediate · 30-120 minutes
Siemens 4115 - Time ratio communication to Ipo changed to
Alarm 4115 fires when machine data MD 10072 (time ratio communication to IPO) is modified to a value less than 1.0, resulting in a calculated cycle time that is not an integer multiple of the position control cycle (typically 4ms). This violates the synchronization requirement between NCK communication and interpolator execution on SINUMERIK 840D systems.
4115
Siemens 4115 - Time ratio communication to Ipo changed to
Time ratio communication to Ipo changed to
The value of the MD10072 $MN_COM_IPO_TIME_RATIO has been adapted. This can only occur, if the value of the machine data is smaller than one and the time thus calculated is no multiple of the position control cycle Control reaction: Alarm display.
Root Cause Summary
Alarm 4115 fires when machine data MD 10072 (time ratio communication to IPO) is modified to a value less than 1.0, resulting in a calculated cycle time that is not an integer multiple of the position control cycle (typically 4ms). This violates the synchronization requirement between NCK communication and interpolator execution on SINUMERIK 840D systems.
Safety
- Only qualified personnel should diagnose and clear control alarms; follow the machine builder's safety procedures and lockout/tagout where hardware work is required.
Causes and Fixes
- 1
Access Siemens HMI or operator panel; navigate to Diagnostics > Machine Data > MD 10072. Document the current value and compare against the machine's position control cycle time (typically found in MD 10073).
Do not modify while CNC is in automatic mode or executing a part program.
- 2
Verify that MD 10072 value, when multiplied by the position control cycle, yields an integer result. For example: if position control cycle = 4ms, MD 10072 must be 1.0, 2.0, 3.0, etc. (not 0.5 or 1.5).
- 3
Reset MD 10072 to the machine builder's default value (typically 1.0 for standard 840D configurations). Save and perform a warm restart (Ctrl+Shift+Del or via PLC menu NC > Initialize).
Warm restart will clear active alarms but retain all program data.
- 4
Verify alarm 4115 clears and confirm communication stability by monitoring NCK cycle counter in Diagnostics > System Info > Cycle Times. Ensure IPO communication indicator shows synchronous status.
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