Register Bit Descriptions
Section Four
GPIB-1014P User Manual
4-26
© National Instruments Corporation
Command Pass Through Register (CPTR)
VMEbus Address:
Base A B (hex)
Attributes:
Read Only
R
7
6
5
4
3
2
1
0
CPT7
CPT6
CPT5
CPT4
CPT3
CPT2
CPT1
CPT0
Bit
Mnemonic
Description
7-0r
CPT[7-0]
Command Pass Through Bits 7 through 0
These bits are used to transfer undefined multiline GPIB command
messages from the GPIB DIO lines to the computer. When the CPT
feature is enabled (CPT ENAB=1, AUXRB[0]w), any GPIB Primary
Command Group (PCG) message not decoded by the TLC is treated as
an undefined command. The multiline GPIB commands recognized by
the
µ
PD7210 are listed in Table 4-3. All GPIB Secondary Command
Group (SCG) messages following an undefined GPIB PCG message are
also treated as undefined. In such a case, when an undefined GPIB
message is encountered, it is held in the CPTR and the TLC Acceptor
Handshake function is held off (in ACDS) until the Valid auxiliary
command is written to the AUXMR. The CPTR is also used to inspect
secondary addresses when mode 3 addressing is used. The TLC
Acceptor Handshake function is held off (in ACDS) until the Valid or
Non-Valid auxiliary command is written to the AUXMR.
Table 4-3. Multiline GPIB Commands Recognized by the
µ
PD7210
Hex Number
Message
Description
01
GTL
Go To Local
04
SDC
Selected Device Clear
05
PPC
Parallel Poll Configure
08
GET
Group Execute Trigger
(continues)