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APPENDIX D
The CRT SRQ number is an octal number based on the binary value of the status byte. This octal number always
begins with a "1" since this is translated from bit 6, the universal HP-IB service request bit. For example, the status
byte for an illegal analyzer command (SRQ 140) is as follows:
bit number
status byte
The CRT displays the octal equivalent of the status byte binary number:
The octal equivalent is based on the whole binary number:
One simple way to determine the octal equivalent of the binary number is to partition the binary number 3 bits at a
time from the least significant bit, and treat each part as a single binary number:
The decimal equivalent of the octal number is determined as follows:
= 96 (decimal).
More than one service request can be sent at the same time. For example, if an illegal analyzer command and the
end of a sweep occurred at the same time, %RQ 144" appears on the CRT display.
bit number
status byte
octal value
Note if bit 1 is set, it has one of three meanings, depending on how SRQ 102 was activated. These meanings are
explained in the following section.
SERVICE REQUEST ACTIVATING COMMANDS
Service requests do not occur
requests: illegal command, SRQ 140, and [SHIFT r] command, SRQ 102 (local operation only). The following
chart summarizes the service request activating commands.
7
0
"SRQ 140"
01100000 (binary) = 140 (octal)
binary
0 1
octal
1
7 6
5 4 3
0 1
1 0 0
1
4
unless
the appropriate activating command has been given, except for two service
6
5
4
3
1
1
0
0
1 0 0
0 0 0
4
0
140 (octal) = 1 * (8) + 4
2 1 0
1 0 0
= "SRQ 144"
4
SERVICE REQUESTS
2
1
0
0
0
0
(8) + 0 * (8)
l
A p p e n d i x 3 5
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