58542 VXIbus Universal Power Meter
2-44 Publication 21555, Rev. E, September 2002
2.5.25 Limit Line Configuration & Monitoring
■ CALCulate:LIMit
The CALCulate:LIMit commands specify and query the status of power measurement limit values and
limit line pass/fail checking. This allows the 58542 to monitor measured values and determine if the
values are outside certain limits or above/below a single limit. The upper limit cannot be specified any
lower than the lower limit; meaning that an exclusion zone of values cannot be specified.
Limit values can be specified separately for either of the two software calculation channels - 1 and 2.
These channels can be specified to correspond to power sensors 1 and 2 (default) or as a combination of
the power sensors. For example, set limit lines to monitor overload or under range conditions on an
amplifier’s output power and gain by specifying channel 1 as sensor 1 limits checking and channel 2 as
Sensor 2/Sensor 1. Power sensor assignments to channel measurement definition is also part of the
CALCulate Subsystem. Limit monitoring can not be performed for individual sensors unless a channel
is configured for single sensor, POW 1 or POW 2 operation.
Upper and Lower limits can be active simultaneously.
Unless serial requests are enabled, the CALCulate:LIMit commands can not be configured to
automatically alert the controller directly during a limit violation; the 58542 must be queried to receive
information regarding pass/fail status of limit line violations.
Automatic notification of limit line violations is accomplished using the status byte and the operation
register. A controller can be notified of a limit line violation via the request service, *SRE command.
After the controller receives the request service, query the event status register. Check the status register
for a limit line violation or send CALCulate:LIMit:FAIL? to check if a limit line is being or has been
violated. 1 indicates a limit line violation. 0 indicates the channel measurement is within the limit
lines.
CALCulate:LIMit
Syntax:
CALCulate<channel 1 to 2>:LIMit:CLEar[:IMMediate]
Example:
OUTPUT @PWR_MTR;CALC1:LIM:CLE ! RESET CHANNEL 1 LIMIT VIOLATION INDICATOR TO 0
Description:
This command resets the limit line pass/fail indicator to 0.
Syntax:
CALCulate<channel 1 to 2>:LIMit:FCOunt?
Example:
OUTPUT @PWR_MTR;CALC1:LIM:FCO? ! QUERIES NUMBER OF CHANNEL 1 LIMIT FAILURES
Response:
Single number; the number of times the limit lines were exceeded.
Description:
This command reports the number of times a limit line has been exceeded since the limit
checking function was set to ON, or the limit line monitor was cleared with CALC#:LIM:CLE.
Syntax:
CALCulate<channel 1 to 2>:LIMit:FAIL?
Example:
OUTPUT @PWR_MTR;CALC1:LIM:FAIL? ! CHECK FOR CHANNEL 1 LIMIT LINE VIOLATION
Response:
0 = OK; 1 = fail
Description:
This command reports whether or not a limit line has been exceeded since the limit checking
function was set to ON, or the limit line monitor was cleared with CALC#:LIM:CLE.
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