ICS ELECTRONICS 4809A, Instruction Manual

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A-5
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 ad-
dress)
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/fe-
male 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