Table of Contents
Advertisement
IEEE-488 Programming
3.6.1 Bus error
A bus error will occur if the instrument receives a device-de-
pendent command when it is not in remote, or if an illegal de-
vice-dependent command (IDDC) or illegal device-
dependent command option (IDDCO) is sent to the instru-
ment. Under these conditions, the complete command string
will be rejected, and the following message will be dis-
played:
In addition, the error bit and pertinent bits in the U1 word
will be set (paragraphs 3.2.13 and 3.2.16), and the instrument
can be programmed to generate an SRQ under these condi-
tions (paragraph 3.2.13).
No Remote error
A no remote error can occur when a command is sent to the
instrument when the REN line is false. Note that the state of
REN is only tested when the X character is received.
IDDC error
An IDDC error can occur when an invalid command such as
H1X is transmitted (this command is invalid because the in-
strument has no command associated with that letter).
IDDCO error
Similarly, an IDDCO error occurs when an invalid option is
sent with a valid command. For example, the command T9X
has an invalid option because instrument has no such trigger
mode.
3.6.2 Number error
A number error occurs when an out of range calibration com-
mand (A) value is sent to the instrument. Under these condi-
tions, the instrument will display the following error
message:
The command string will be accepted, but the calibration val-
ue will remain unchanged.
3-24
b Err
n Err
3.6.3 Trigger overrun error
A trigger overrun error occurs when the instrument receives
a trigger while it is still processing a reading from a previous
trigger. Note that only the overrun triggers are ignored and
will have no effect on the instrument except to generate the
message below. When a trigger overrun occurs, the following
front panel message will be displayed for approximately one
second:
3.7
Bus data transmission times
A primary consideration is the length of time it takes to ob-
tain a reading once the instrument is triggered to make a con-
version. The length of time will vary somewhat depending
on the selected function and trigger mode. Table 3-4 gives
typical times.
Table 3-4
Trigger to reading-ready times
Configuration
2V, 20V, 200V
200mV
20nA, 200nA, 20µA,
200µA, 20mA
20pA, 200pA
2nA, 2µA, 2mA
2pA
2nC, 20nC
200pC
20kΩ-200GΩ
2kΩ
NOTES:
1. Conditions: Input is on range, and times may depend on controller
used.
2. Preamp settling time (to 12%) is 2 seconds on preamp ranges (2, 20,
200pA), and must be taken into account by the user.
3. Volt time/error also applies to external feedback.
t Err
Time
Error (1% of
(msec)
step input)
365
0.01
780
0.1
365
0.01
2
365
55
780
0.1
2
780
25
365
0.01
780
0.1
365
0.01
780
0.1
Advertisement
Table of Contents
