20170

Common Causes

• Machine data $MC_NUM_AC_FIFO, $MC_START_AC_FIFO, $MC_LEN_AC_FIFO, or $MC_MODE_AC_FIFO configured with values that exceed available R parameter space
• R parameter field size defined in $MC_MM_NUM_R_PARAM is too small for the calculated FIFO structure
• FIFO configuration parameters conflict with reserved or allocated R parameter ranges
• Machine data parameters were modified without recalculating total R parameter requirements
• Multiple channels configured with overlapping or excessive FIFO memory allocations

Troubleshooting Steps

1. 1Review current machine data settings for $MC_NUM_AC_FIFO, $MC_START_AC_FIFO, $MC_LEN_AC_FIFO, and $MC_MODE_AC_FIFO in the affected channel
2. 2Calculate total R parameter space required: (number of FIFOs × length per FIFO) and verify against available space defined by $MC_MM_NUM_R_PARAM
3. 3Check machine data documentation to confirm FIFO configuration aligns with R parameter allocation and does not overlap with other reserved parameters
4. 4Reduce FIFO count ($MC_NUM_AC_FIFO) or length ($MC_LEN_AC_FIFO) values, or increase $MC_MM_NUM_R_PARAM if sufficient memory is available
5. 5Power cycle the control after correcting machine data and verify alarm clears on next startup