Watkins-Johnson Company WJ-8718-19/FE Instruction Manual page 71

INSTALLATION AND OPERATION
WJ-8718-19/FE HF RECEIVER
2.4.8.2.4 Data Information Definition
Byte 2 is the Data Information Definition (DID) Byte, as shown in Table
2-11. The three most significant bits of the DID byte are a binary code (111) which
uniquely defines Byte 2 as a DID byte. The 2 bit of the DID byte is the
command/monitor bit, which defines the function of the data bytes to follow Byte 2
If the 2^ bit is logic 1, the controller desires to command the receiver and will
transmit receiver parameter data in the byte or bytes to follow Byte 2. If the 2 bit
is logic 0, the controller desires to monitor the receiver; the receiver will transmit
the address byte (paragraph 1.5.2.3), and the byte or bytes that follow will contain
the current status of the addressed receiver (transmitted by the receiver).
1
26
1
DID
Byte Code
25
Table 2-11. DID Byte
24
C/M S/A Register
0 0 0 - 1 1 0
C/M = Command (1) or Monitor (0)
S/A = Single (1) or All (0) Bytes
The 23 bit of the DID defines the number of data bytes to succeed Byte 2;
a logic 1 indicates a single byte and a logic 0 indicates all bytes.
The remaining three bits of the DID byte contain a binary coded register
address. All receiver parameters are stored in seven 8-bit registers, addressed in
binary code from 0 through 7. If all parameter data are to be transmitted, the logic
levels of the three register address bits are irrelevant; however, if one word of
receiver parameter data is to be transmitted, the 3-bit binary code for the desired
register must be established in the 20, 21, and 22 bits of the DID byte (paragraph
2.4.8.2.4).
2.4.8.2.5 Data Bytes
If all receiver parameters are to be controlled, the bytes following the DID
Byte will contain data transmitted from receiver to controller or from controller to
receiver, as listed in Table 2-12. If all receiver parameters are to be monitored, Byte
3 will be the address return byte followed by data, Bytes 4 through 10. Transmission
of less than complete parameter data requires that the register associated with a
articular byte of data be addressed in the DID byte. The selected data will then be
transmitted as Byte 3 or 4. Paragraphs 2.4.8.2.7 and 2.4.8.2.8 contain examples of data
formats for full and partial status transmissions, in monitor and command modes.
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2-46