A-5
A1
A
EOI (end or identify) is used by a device to indicate the end of a multiple-
byte transfer sequence. When a controller-in-charge sets both the ATN and
EOI lines true, each device configured to respond to a parallel poll indicates
its current status on the DIO line assigned to it.
Bus Commands are transmitted when ATN is asserted. The commands are
listed in the message columns in Table 1 (on the left hand page) which
shows the relationship between the commands and ASCII data characters.
ASCII data characters have the same code values as bus commands but are
transmitted with ATN off. The following chart lists the standard command
and address mnemonics.
Address Commands
MLA
My listen address (controller to self)
MTA
My talk address (controller to self)
LAD
Device listen address
TAD
Device talk address
SAD
Secondary Device address (device optional address)
UNL
Unlisten
UNT
Listen
Universal Commands (to all devices)
LLO
Local Lockout
DCL
Device Clear
PPU
Parallel Poll Unconfigure
SPE
Serial Poll Enable
SPD
Serial Poll Disable
Addressed Commands (to addressed listeners only)
SDC
Selected Device Clear
GTL
Go to Local
GET
Device Trigger
PPC
Parallel Poll Configure
TCT
Take Control
Devices on the bus are normally interconnected by cables with dual male/
female connectors at each end to allow easy cable stacking. The 24
conductor cable pinouts are shown in Figure A-2. Signal levels are 0 and
3.3 Vdc with 0 being the logic true level. Cable connectors are modified
Amphenol 24 pin Blue ribbon style connectors (57-30240) with metric jack
screws.
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