Code SRVO-038: Pulse mismatch (G:%d A:%d)
Issue Description & Safety Warning
The Fanuc R-30i Series Robot Controller has triggered a critical Pulse mismatch (G:%d A:%d) alarm. Immediate attention from a qualified operator or maintenance technician is required to prevent secondary damage to the equipment or spoiled parts during the manufacturing cycle. Always ensure standard safety and LOTO procedures are followed before accessing electrical cabinets.
Official Troubleshooting Steps
Cause: A pulse count detected at power-on differs from one detected at power-off. This could be due to the following: 1. File (SYSMAST.SV) that saved in the state at an axis position different from a present axis position was loaded. 2. The software brake setting is incorrect. 3. A incorrect brake type was set to the robot with two-axis brake option. 4. File (SYSMAST.SV) that saved with other robots was loaded. 5. The axis position was changed with a brake release unit while the controller power is off. 6. The axis fell while the controller power is off due to the brake trouble. Remedy: 1. Refer SRVO-222 when this error occurs with SRVO-222. 2. For the above cause 2 and 3, confirm the setup or brake type setting and correct setting. For the above cause 4, re-load SYSMAST.SV of the robot. Afterwards, PULSE RESET operation should be done. There are the following two methods. • Method 1: Move the cursor to $MCR.$SPC_RESET on the system variable screen, and select F4 TRUE. It becomes TRUE momentarily, it writes in FALSE at once. Then push the reset button. • Method 2: F3 RES_PCA is pushed on the MASTER/CAL screen, and select F4 YES. Then push the alarm release button. Note) The MASTER/CAL screen is not usually displayed. The worker who has the operation qualification does. Check whether the robot position on Teach Pendant is correct. If incorrect, re-mastering is required.
Source: FANUC Robot R-30iA Alarm Code List Operator's Manual
Last reviewed: 2026-07-01 · Verified against the manufacturer’s official documentation.
About Fanuc R-30i Series Robot Controller Alarms
Fanuc controllers include extensive self-diagnostics that flag or halt the machine when a fault is detected. Error code SRVO-038 on the R-30i Series Robot Controller identifies one specific fault condition — its documented cause and the official corrective steps are listed above, sourced from Fanuc's service documentation. Always confirm against the manual for your exact machine configuration and follow LOTO procedures before servicing.
Complete Alarm List: 6553 Fanuc R-30i Series Robot Controller codes.
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