SECTION3
IEEE-488
Reference
3.7 TIMING CONSIDERATIONS
Timing considerations for IEEE-488 programming in-
clude:
• Data transfer rates between the controller
and
Model
236/237/238 over the IEEE-488 bus.
•
Command string parse time within the Source Meas-
Ure
Unit.
•
Execution times of the tasks defined
by
device-de-
pendent commands.
The
times needed for these actions are determined by the
length of the command string, the types of commands,
and
the speed of the controller.
+
Typically, a command string sent to the Model
236/237/238
will
transmit
at
a rate of five characters
per
millisecond. (Assuming the transfer speed of the control-
ler does
not
affect the listening rate of the Model
236/237 /238.) For example, the command string
"Q1,1,10,1,2,50X"
will take 3msec to transmit from the
controller
to
the Model236/237 /238.
When the Source Measure
Unit
is sending
data
to the
controller (e.g., uploading sweep data), the transmission
rate
will
typically
be
2.5 characters
per
millisecond.
The
bus
hold-off time for each command is the time from
receipt
of
the
''X"
to
"instrument configured"
.It
includes
the parsing time
and
command execution time. Table 3-8
summarizes the
bus
hold-off times for device-dependent
commands.
Table
3-8. Typical
Bus
Hold-off
Times
Description
Command
Time
Modify Sweep List
Al,
1, 1, 1, 2 8.2msec
Bias Operation
Bl, 1,1 18.6msec
Display
01,236
7.9msec
D2,236 316.3msec
DOX
14.4msec
Source
and
Function Fl,O
64.0msec
Output
Data Format
G15,0, 0
8.3msec
IEEE
Immediate Trigger
HOX
14.2msec
Restore Factory Defaults
JO
1.13sec
EOI
and
Bus Hold-offs
Kl
7.2msec
Compliance
L.001,7 30.6msec
SRQ Mask
and
Serial Poll Byte
Ml,l
13.1msec
Operate
Nl
13.6msec
Output
Sense
01
11.6msec
Filter
Pl
13.6msec
Create/
Append
Sweep List
QO,
1,
0, 0, 10
71.7msec
QO,
1,2,
1,1
39.9msec
Trigger Control
RO
7.5msec
Integration Time
51
28.6msec
52
64.5msec
Trigger Configuration
TO,
0,
0, 0 15.5msec
Status
uo
7.5msec
llOOV
Range Control
VOorVl
11.6msec
Default Delay
wo
12.6msec
Execute X 6.4msec
Terminator
Yl
7.5msec
Suppress
Zl
10.7msec
Note: The Model
'236/'2:37
/'138
is
placed
in
power-up
default conditions before each
command
is sent.
3-82
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