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Register Bit Descriptions Chapter 4
GPIB-1014 User Manual 4-10 © National Instruments Corporation
Bit Mnemonic Description
undefined: GPIB command not automatically recognized and
executed by TLC
ACDS: GPIB Accept Data State
CPT ENABLE: AUXRB[0]w
UDPCF: Undefined Primary Command Function
SCG: GPIB Secondary Command Group message
pon: Power On Reset
TAG: GPIB Talk Address Group message
LAG: GPIB Listen Address Group message
read ISR1: Bit is cleared immediately after it is read
UDPCF is set on:
[UCG + ACG & (TADS + LADS)] & undefined & ACDS & CPT
ENABLE
UDPCF is cleared on:
[(UCG + ACG) & defined + TAG + LAG] & ACDS + CPT
ENABLE* + pon
The CPT bit flags the occurrence of a GPIB command not recognized
by the TLC, and all following GPIB secondary commands when the
Command Pass Through feature is enabled by the CPT ENABLE bit,
AUXRB[0]w. Any GPIB command message not decoded by the TLC
is treated as an undefined command; however, any addressed
command is automatically ignored when the TLC is not addressed.
Undefined commands are read using the Command Pass Through
Register (CPTR). The TLC holds off the GPIB Acceptor Handshake
in the Accept Data State (ACDS) until the Valid auxiliary command
function code, 0F hex, is written to the AUXMR. If the CPT feature is
not enabled, undefined commands are simply ignored.
6r APT Address Pass Through
6w APT IE Address Pass Through Interrupt Enable
APT is set by:
ADM1 & ADM0 & (TPAS + LPAS) & SCG & ACDS
APT is cleared by:
pon + (read ISR1)
Notes
ADM1: Address Mode Register Bit 1, ADMR[1]w
ADM0: Address Mode Register Bit 0, ADMR[0]w
TPAS: GPIB Talker Primary Addressed State
LPAS: GPIB Listener Primary Addressed State