Fluke A20M-AF ユーザーズマニュアル

© 2007 DH Instruments, a Fluke Company 

Page 98 

The RPM4 contains an 8 bit Status Byte Register that reflects the general status of the RPM4. 

Table 16.  8 Bit status byte register 

(128) 

(64) 

(32) 

(16) 

(8) 

(4) 

(2) 

(1) 

 

This register is affected by the RPM4 reply output queue, the Error Queue, the Standard 
Event Status register and the Ready Event Status register. 

 

Status Byte Register 

(“

∗

STB?”  or  ”

∗

SRE n”)

 

(128) 

 

(64) 

Standard Event Status Register 

(“

∗ESR?”  or  “∗ESE n”) 

(32) 

←←← 

(128) 

(64) 

(32) 

(16) 

(8) 

(4) 

(2) 

(1) 

(16) 

←←← 

QUEUE 

 

(8) 

 

(4) 

←←← 

QUEUE 

 

(2) 

Ready Event Status Register 

(“RSR?”  or  ” RSE n”) 

(1) 

←←← 

(128) 

(64) 

(32) 

(16) 

(8) 

(4) 

(2) 

(1) 

Figure 11.  Status register schematic 

The Status Byte Register can be read using the “*STB?” query, or by performing a serial poll 
on the IEEE-488 bus.  If you read this using a serial poll then Bit 6 is the RQS.  If the 
“*STB?” query is used, then bit 6 is the MSS bit.  All of the other bits are common to both 
types of query. 

Each of these status bits can cause a SRQ to occur.  The Service Request Enable Register 
(“*SRE” program message ) determines which of these flags are able to assert the SRQ line.  
This enable register has a matching set of bits that each will enable the designated bit to 
cause a SRQ, except for the RQS/MSS bit(s) which cannot cause a SRQ.  If you set this 
register to 20 ($14 hex), an SRQ will occur if the MAV or the ERROR bit are set.  The 
description of these bits are given as: 

N/A Bit 7 (128) 

Requested Service Bit 6 (64) 
Indicates that the SRQ line of the IEEE-488 interface has been asserted by the 
RPM4.  This bit is cleared when a serial poll is performed on the RPM4, and is a 
part of the Status Byte Register when read using a serial poll.  This bit does not 
apply if the COM1 port is being used. 

MSS 

Master Summary Status Bit 6 (64) 
Indicates that an event or events occurred that caused the RPM4 to request service 
from the Host, much like the RQS bit.  Unlike the RQS bit, it is READ ONLY and can 
be only cleared when the event(s) that caused the service request are cleared. 

ESB 

Event Summary Bit 5 (32) 
Indicates if an enabled bit in the Standard Event Status Register became set  
(see Section 4.5.3).