3-10
3
The 4899A generates a service request (SRQ) whenever any of the enabled
bits in the Status Byte Register become true and the 4899A is not addressed
as a talker. The Status Byte Register may be read by a Serial Poll or with
the
*STB?
query. A Serial Poll resets the RQS bit; the
*STB?
query does
not change the bit. The Status Byte Register is enabled by setting the
corresponding bits in the Service Request Enable Register with the
*SRE
command. e.g.
*SRE 160
‘Sets the SRE Register to 1010 0000 which
enables just the Event Status and Questionable
summary bits to generate SRQs.
3.4.8 Saving the Enable and Transition Register Values
The Enable and Transition Register values can only be saved and recalled
at power turn-on by disabling the PSC flag.
The *SAV command does not
save the Enable and Transition register values.
Use the *PSC 0 com-
mand to disable the PSC flag and save the current Enable and Transition
register values. The following example saves the current settings which
enables bits in the Operation and Event Status Registers to generate a SRQ
at power turn-on. e.g.
STAT:OPER:ENAB 1
‘enables bit 1
STAT:OPER:NTR 1
‘enables negative transition
*ESE 192;*SRE 32;*PSC 0
‘saves ESE and SRE bits
as power on settings.
Note that the enable and transition commands must be on the same line or
set prior to the *PSC 0 command to be saved. A later *PSC 1 command
sets the PSC flag which will cause the registers to be cleared at the next
power turn-on. The Enable and Transition Register values can be set or
changes at any time by program commands.
3.4.9 488.2 Differences from 488.1 Devices
The IEEE 488.1 Device Clear command
does not
reset the unit’s input-
output settings as would be expected of a 488.1 device. To reset the unit’s
input-output settings, use the *RST (Reset) or *RCL 0 command.
3.5
488.2 CONFORMANCE INFORMATION
Summary of Contents for 4809A
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