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Appendix A
Fixed Formats
Any Query (
)command or Status (
?
up to 65,535 always returns five digits, so zero would be returned as
descriptions, leading zeros are included. They are not, however, required when entering the command.
Conflict Errors
Some combinations of commands and parameters can be sent to the unit that are out of range for a particular
configuration or inconsistent with other commands. For instance, specifying a Scan Interval (
less time than the unit can acquire scans results in a conflict error:
PRINT#1,"C1-992,I00:00:00.0,00:00:00.0X"
A conflict error lights the ERROR indicator LED on the scanning unit and returns an E4 when queried with the
Error Query (
) command. Some conflict errors result in a default value for a conflicted command. For
E?
instance, in the example above, the scan interval defaults to the fastest possible scan interval for the number of
defined channels.
Command Interpretation
As commands are received by the unit, they are interpreted in the order in which they are received. Some
commands are immediate, which means they immediately take effect. Other commands are deferred and have
no effect on device operation until the Execute (
Immediate & Deferred Commands
The immediate and deferred commands applicable to NetScan are listed in a table on the following page.
An example of an immediate command is Set Digital Outputs (On), which immediately chooses the digital
output line which is being referred to.
An example of a deferred command is Set Data Format (
for channel data when
in internal temporary registers. As additional deferred commands are interpreted, their effects are added to these
registers, possibly overwriting earlier effects. Finally, when
examined in the execution order described below. If two deferred commands that do not affect the same
function are received before the Execute (
If a deferred command is sent multiple times within a command line, the last occurrence of the command will
take precedence. Note that a command line is terminated by the
data output format will be as specified by the
takes effect.
If an error is detected during command processing, commands are ignored up through and including the next
execute command. Thus, any immediate commands after the error, (and all deferred commands) are ignored.
For example, the command line
executes the
, because it is an immediate command that occurred before the error. The deferred commands
O0
and
T1,1,0,0
T3,7,0,0
Deferred commands help reduce the effects of errors and improve synchronization of command execution. The
primary advantage of deferred commands is that they are executed as a group, either all or none. If any errors
occur, deferred commands have no effect and the device is left in a consistent state instead of a partially
modified, inconsistent state.
NetScan User's Manual
) command returns a fixed format. For instance, any option that can range
U
X
is interpreted. As deferred commands are interpreted, their desired effects are recorded
X
)command, they take effect in the execution order described below.
X
F1,3X
T1,1,0,0O216,0,25, 255AAT3,7 K20 X
and the immediate command
00000
) command is interpreted.
), which determines the input and output format used
F
is interpreted, the temporary registers are
X
. For example, if
X
command. The
F1,1
after the error have no effect.
K20
API Command Reference
. In the following command
) command to
I
is sent, the
F1,1 F1,3X
command is overridden and never
containing the error
AA
only
A-3
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