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Figure 4-1. the model 187 status system, Remote interface reference, Scpi status system – American Magnetics 187 Self-Compensating Liquid Level Controller User Manual

Page 42

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Remote Interface Reference

SCPI Status System

A condition register continuously monitors the state of the instrument.
The bits of a condition register are updated in real time. A condition
register is read-only and is not cleared when you read the register. A query
of a condition register returns a decimal value in the appropriate output
buffer which corresponds to the binary-weighted sum of all bits set in the
register.

An event register latches various events. An event register is not buffered,
therefore once a bit is set, further occurrences of that event are ignored.
Once a bit is set in an event register, the bit remains set until the register
is read (

*ESR?

) or a

*CLS

(clear status) command is issued. A query of an

event register returns a decimal value in the appropriate output buffer
which corresponds to the binary-weighted sum of all bits set in the
register.

An enable register (or bitmask) defines which bits in an event register are
reported to the Status Byte register group. An enable register can be both
written and queried. The

*CLS

(clear status) command does not clear an

Fill Expired

0

1

2

3

4

5

6

7

<1>

<2>

<4>

<8>

<16>

<32>

N/A

<128>

*SRE <

value

>

*SRE?

Serial Poll

*STB?

C

EN

Summary Bit (RQS)

"OR"

Status Byte Registers

0

1

2

3

4

5

6

7

<1>

<2>

<4>

<8>

<16>

<32>

<64>

<128>

*ESE <

value

>

*ESE?

*ESR?

EV

EN

"OR"

Standard Event Registers

Operation Complete

Query Error

Device Error

Execution Error

Command Error

Power On

IEEE-488 Output Buffer

Serial Output Buffer

NOTES:
C = Condition Register
EV = Event Register
EN = Enable Register

0

1

2

3

4

5

6

7

<1>

<2>

<4>

<8>

<16>

<32>

<64>

<128>

STATus:ALARm:ENABle <

value

>

STATus:ALARm:ENABle?

STATus:ALARm:EVENt?

EV

EN

"OR"

Alarm Registers

HI Alarm

B Alarm

LO Alarm

RATE Alarm

A Alarm

0

1

2

3

4

5

6

7

C

Fill State

STATus:ALARm:COND?

Over/Under Flow

Max Dielectric

Exceeded

Figure 4-1. The Model 187 status system.