Aquadopp Checksum Calculation

Can someone tell me how to compute the checksum the Aquadopp sends?  Here's a sample from the head configuration, in hex.
I cannot figure out how to get '89c6' from the values that precede it,
with or without the 'b58c' offset listed in the manual.

a50470000800e803000041535020313537390000000019001900190000003d1960f360f3000024eadc15e205e2

05e20500000000004000000000000000400000000000000000ffff00000100000001000000000000000000ffff

0000ffff0000ffff000000000000ffff010000000000ffffffff00000000000000101027472e7949114bb46800

000000004000000000000000400000000000000000000000000000000000000000000000000000000000000000

00000000000000000000e913100e100e1027640000000000000000000000000000000000000000000300896c

Checksum computation is described in the System Integrator Guide which is available on request. Unfortunately there is a misprint in the data structures section of the manual saying that the checksum is computed in characters. It should read words (shorts), not bytes. Sorry for the inconvenience.

Best regards,
Oistein Hurum