Technical data

Power Meter Remote Operation 1

N1911A/1912A P-Series Power Meters Programming Guide 67

Using the Operation Complete Commands

The *OPC? and *OPC commands allow you to maintain synchronization

between the computer and the power meter. The *OPC? query command

places an ASCII character 1 into the power meter’s output queue when all

pending power meter commands are complete. If your program reads this

response before continuing program execution, you can ensure

synchronization between one or more instruments and the computer.

The *OPC command sets bit 0 (Operation Complete) in the Standard Event

Status Register when all pending power meter operations are complete. By

enabling this bit to be reflected in the Status Register, you can ensure

synchronization using the GPIB serial poll.

Procedure

• Send a device clear message to clear the power meter’s output buffer.

• Clear the event registers with the *CLS (clear status) command.

• Enable operation complete using the *ESE 1 command (standard event

• Send the *OPC? (operation complete query) command and enter the

result to assure synchronization.

• Send your programming command string, and place the *OPC

(operation complete) command as the last command.

•Send the *STB? (status byte query) command to poll the register. This

command does not clear the status byte summary register.

In GPIB mode only you can use a serial poll to check to see when bit

5 (standard event) is set in the status byte summary register. You could

also configure the power meter for an SRQ interrupt by sending *SRE

32 (status byte enable register, bit 5).

Examples

This example program uses the *OPC? command to determine when the

NOTE

For LAN and USB use the *STB? command. See “Using *STB? to Read the Status

Byte” on page 60.