DH Instruments MFC-CB, Руководство по эксплуатации и обслуживанию

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4. REMOTE OPERATION
Page 75
©2001~2007 DH Instruments, a Fluke Company
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 an 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 an SRQ, except for the RQS/MSS bit(s) which
cannot cause an 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:
•
OPER: OPERational event register summary bit (Bit 7)
This bit is not supported by the MFC-CB.
• RQS: Requested Service (Bit 6)
Indicates that the SRQ line of the IEEE-488 interface has been asserted by
the MFC-CB. This bit is cleared when a serial poll is performed on the MFC-CB,
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)
Indicates that an event or events occurred that caused the MFC-CB 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 (Bit 5)
Indicates if an enabled bit in the Standard Event Status Register became set.
(See Section 4.4.1.2.)
• MAV: Message Available Bit (Bit 4)
Indicates that at least one reply message is waiting in the MFC-CB IEEE-488
output queue.
• ERR: Error Queue not empty (Bit 2)
Indicates that at least one command error message is waiting in the MFC-CB
IEEE-488 error message queue. Use the “ERR” command to get this message.