User manual

15-2 Status Structure 2400 Series SourceMeter

User’s Manual

Overview

The SourceMeter provides a series of status registers and queues allowing the

operator to monitor and manipulate the various instrument events. The status

structure is shown in Figure 15-1. The heart of the status structure is the Status

Byte Register. This register can be read by the user's test program to determine if

a service request (SRQ) has occurred, and what event caused it.

Status byte and SRQ

The Status Byte Register receives the summary bits of four status register sets

and two queues. The register sets and queues monitor the various instrument

events. When an enabled event occurs, it sets a summary bit in the Status Byte

enable bit is set (as programmed by the user), the RQS/MSS bit will set to indicate

that an SRQ has occurred.

Status register sets

A typical status register set is made up of a condition register, an event register

and an event enable register. A condition register is a read-only register that con-

stantly updates to reflect the present operating conditions of the instrument.

When an event occurs, the appropriate event register bit sets to 1. The bit remains

latched to 1 until the register is reset. When an event register bit is set and its cor-

responding enable bit is set (as programmed by the user), the output (summary)

of the register will set to 1, which in turn sets the summary bit of the Status Byte

Queues

The SourceMeter uses an Output Queue and an Error Queue. The response mes-

sages to query commands are placed in the Output Queue. As various program-

ming errors and status messages occur, they are placed in the Error Queue.

When a queue contains data, it sets the appropriate summary bit of the Status

Byte Register.