This integer value specifies the number of valid bits used for the Control field buffer length and Status field bytes transferred in the Scatter/Gather descriptors. It also specifies the number of valid bits in the RX Length of the Status Stream App4 field when Use Rxlength is enabled. For Direct Register Mode, it specifies the number of valid bits in the MM2S_LENGTH and S2MM_LENGTH registers. The length width directly correlates to the number of bytes being specified in a Scatter/Gather descriptor or number of bytes being specified in App4.RxLength, MM2S_LENGTH, or S2MM_LENGTH. The number of bytes is equal to 2 Length Width . So a Length Width of 26 gives a byte count of 67,108,863 bytes. This value should be set to 23 for Multichannel mode.