Ieee488 Bus Lines; Bus Management Lines - Keithley 706 Instruction Manual

12. LE (Extended Listener Capabilities)-The Model 706
does not have extended listener capabilities.
Table 3-2. Model 708 Interface Function Codes
Code
SHl
AH1
T6
L4
SRI
RLl
PPO
DC1
DTI
co
El
TEO
LEO
Interface Function
Source Handshake Capability
Acceptor Handshake Capability
Talker (Basic Talker, Serial Poll,
Unaddressed To Talk On LAG)
Listener (Basic Listener, Unaddressed
To Listen On TAG)
Service Request Capability
Remote/ Local Capability
No Parallel Poll Capability
Device Clear Capability
Device Trigger Capability
No Controller Capability
Open Collector Bus Drivers
No Extended Talker Capabilities
No Extended Listener Capabilities
3.1.4 Model 706 Interface Commands
Interface commands controlling Model 706 operation are
listed in Table 3-3. Not included in the table are device-
dependent commands, which are covered in detail in
paragraph 3.5.
Table 33. IEEE Command Groups
HANDSHAKE COMMAND GROUP
DAC = DATA ACCEPTED
RFD = READY FOR DATA
DAV=DATA VALID
UNIVERSAL COMMAND GROUP
ATN = ATTENTION
DCL = DEVICE CLEAR
IFC = INTERFACE CLEAR
LLO = LOCAL LOCKOUT
REN = REMOTE ENABLE
SPD = SERIAL POLL DISABLE
SPE = SERIAL POLL ENABLE
ADDRESS COMMAND GROUP
LISTEN: LAG = LISTEN ADDRESS GROUP
MLA = MY LISTEN ADDRESS
UNL=UNLISTEN
TALK: TAG =TALK ADDRESS GROUP
MTA = MY TALK ADDRESS
UNT = UNTALK
gmTh = fJJ-ER Tfil& AjI$!ESS
ADDRESSED COMMAND GROUP
ACG =ADDRESSED COMMAND GROUP
GET= GROUP EXECUTE TRIGGER
GTL= GO TO LOCAL
SDC= SELECTIVE DEVICE CLEAR
STATUS COMMAND GROUP
RQS = REQUEST SERVICE
SRQ= SERIAL POLL REQUEST
STB = STATUS BYTE
END = EOI
3.2 IEEE-488 BUS LINES
As shown in Figure 3-1, the signal lines on the IEEE-488 bus
are divided into three groups; management, handshake, and
data lines. The management and handshake lines ensure that
proper data transfer and bus operation takes place while the
data lines handle the bus information. Each of the bus lines
are low (true).
TO OTHER DEVICES
ICOMPUTERJ
TALK AND
DATA BUS
>ATA BYTE
TRANSFER
CONTROL
GENERAL
INTERFACE
UANAGEMENT
DlOl... 8 DATA I8 LINES)
BUS MANAGEMENT
Figure 3-l. Bus Structure
3.2.1 Bus Management Lines
The bus management group consists of five signal lines that
send certain single line bus commands and ensure an orderly
transfer of data. The five signal lines are:
1. ATN (Attention)-The state of the ATN line determines
whether information placed in the data bus by the con-
troller is to be considered data or a command.
2. REN (Remote Enable)-Setting the REN line low (true)
sends the REN command and sets up the instrument on
the bus for remote operation. If REN is followed by the
primary address df the Model 706, then it will be the only
instrument to be placed in the remote mode.
3-3