Measurement Computing DBK70 - Manual (Page 69)

DBK70 User’s Manual 928494 Fundamentals of Obtaining Vehicle Data 6-3
The Filter field defines a bit pattern which is compared with network messages. The DBK70 compares
each message on the network with the hexadecimal pattern in the Filter. When a match is found, the
attached data is captured, scaled, and output on the assigned analog output. The Filter is one or more two
byte sets, typically 5 or 6 sets to match the message size. Hexadecimal coding is used. The Filter definition
must contain a 2-byte-set (4 hex characters) for every byte in the message that is to be compared.
A 5 byte message header would require a Filter definition of 10 bytes (20 characters), for example.
The first byte of a 2-byte-set defines the bit-by-bit data values that must be matched by a received message
in order to be passed by the filter and processed by an output channel. The second byte of a 2-byte-set is
a mask byte that defines which bits are to be checked for a match.