Fluke 5502A, Руководство оператора

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5502A
Operators Manual
5-40
7 6 5 4 3 2 1 0
0
RQS
MSS
ESB MAV EAV ISCB 0 0
Re qu esting ser v ice. The RQS b it is set to 1 w hene v er b its ESB, MA V , EA V , or ISCB
change from 0 to 1 and are ena b led (1) in the SRE. W hen RQS is 1, the 5502A
asserts the SRQ control line on the IEEE-4 88 interface. Yo u can do a serial poll to read
this b it to see if the 5502A is the so u rce of an SRQ.
Master s u mmary stat u s. Set to 1 w hene v er b its ESB, MA V , EA V , or ISCB are 1 and
ena b led (1) in the SRE. This b it can b e read u sing the *STB? command in serial
remote control in place of doing a serial poll.
Set to 1 w hen one or more ena b led ESR b its are 1.
Message a v aila b le. The MA V b it is set to 1 w hen data is a v aila b le in the IEEE-4 88
interface o u tp u t bu ffer of the 5502A.
Error a v aila b le. An error has occ u rred and an error is a v aila b le to b e read from the
error qu e u e b y u sing the ERR? qu ery.
One or more ena b led ISCR b its are 1.
RQS
MSS
ESB
MA V
EA V
ISCB
gjh035.eps
Figure 5-9. Serial Poll Status Byte (STB) and Service Request Enable (SRE)
Service Request (SRQ) Line
IEEE-488 Service Request (SRQ) is an IEEE-488.1 bus control line that the Calibrator
asserts to tell the controller that some type of service is necessary. Many instruments can
be on the bus, but they all share a single SRQ line. To find which instrument set SRQ, the
Controller typically does a serial poll of each instrument. The calibrator asserts SRQ
when the RQS bit in its Serial Poll Status Byte is 1. This bit tells the controller that the
Calibrator was the source of the SRQ.
RS-232 Remote operations with the RS-232 interface emulate the IEEE-488 SRQ line
with an SRQSTR string sent with the serial interface when the SRQ line is set. (See the
SRQSTR command description in Chapter 6 for more information.)
The Calibrator clears SRQ and RQS when the controller/host does a serial poll, sends
*CLS, or when the MSS bit is cleared. The MSS bit is cleared only when ESB, MAV,
EAV, and ISCB are 0, or they are disabled by their associated enable bits in the SRE
register being set to 0.
Service Request Enable Register (SRE)
The Service Request Enable Register (SRE) enables or masks the bits of the Serial Poll
Status Byte. The SRE is cleared at power up. Refer to Figure 5-9 for the bit functions.