Chapter 3 Programming Your Universal Counter for Remote Operation

Elements of SCPI Commands

Using the Standard Event Status Register to Trap an Incorrect HP-IB command— Example 2

The following command grouping shows how to use the Standard Event Status Register and the Status Byte Register to alert the computer when an incorrect command is sent to the Counter.

The command *ESE 32 tells the Counter to summarize the command error bit ( bit 5 of the Event Status Register) in the Status Byte Register. The command error bit is set when an incorrect command is received by the Counter. The command *SRE 32 tells the Counter to assert the SRQ line when the Event Status Register summary bit is set to 1. If the Counter is serial polled after a command error, the serial poll result will be 96.

Event Status Register

*ESE 32 Enable for bad command.

*SRE 32 Assert SRQ from Standard Event Status Register summary.

Using the Questionable Data/Signal Status Register to Alert the Computer When Automatic Interpolator Calibration is Disabled— Example 3

The default operation of the Counter is for automatic interpolator calibration to occur before every measurement. To optimize throughput over the HP-IB, the automatic calibration can be disabled. When it is disabled, the most recent calibration values are used. These values may not be the optimal values for a particular temperature or other environmental condition. For this reason,

the Time, Frequency and Phase bits in the Questionable Data register are set whenever the automatic calibration is disabled.

In the following Questionable Data Status Register example, the first line tells the Counter to detect a transition from negative

(non-questionable data) to positive (questionable data) of bits 2, 5, and 6 in the Questionable Data Register. The next line tells the Counter to summarize the detected events in the Status Byte Register. The command *SRE 8 tells the Counter to assert the SRQ line when the summary bit for the Questionable Data register is set to 1. A serial poll will return the value 72 when the automatic calibration transitions from on to off.

Programming Guide

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