Welltech SPCI2S Intel NetStructure SS7 Boards - Manual (Page 94)

SS7 Programmer’s Manual for SPCI2, SPCI4 and CPM8 Issue 2 Page 94
The frame format taken from the following table:
frame_format Description
1 E1 double frame (E1 only)
2 E1 CRC4 multiframe (E1 only)
4 D3/D4 (Yellow alarm = bit 2 in each channel) (T1 only)
7 ESF (Yellow alarm in data link channel) (T1 only)
The CRC mode taken from the following table:
crc_mode Description
1 CRC generation disabled
2 CRC4 enabled (frame_format must be set to 2)
3 CRC4 compatibility mode (frame_format must be set to 2)
4 CRC6 enabled (frame_format must be set to 7)