Anritsu ML2437A - Getting a Reading; Service Request Status (SRQ); Rgh; Lim

488.2 Command Format GPIB Operation
8-8 PN: 10585-00001 Rev. P ML2437A/38A OM/PM
Getting a Reading
The 488.2 standard requires that the data can only be read from the device after it has been
requested. Any data requested from the device is made available to be read, and is stored in
an output buffer.
As long as there is data in the output buffer to be read, the Message AVailable (MAV) bit in
the status byte is set. This bit allows data to be requested and, as soon as the data is
available, the MAV bit is set, from which a service request can be produced (SRQ).
The ML243X allows this output buffer to be turned off using the BUFF OFF command. In
this mode of operation, if a number of data requests are made with out reading the data after
each request, only the last data requested is available. Note that this does not include the
serial poll request which is handled independently.
Service Request Status (SRQ)
The System Service Request Status byte available over GPIB by a serial poll is defined as
follows:
RGH
If a sensor goes over or under the operating range, this bit is set. This bit can be used to set an
SRQ by setting the same bit in the SRE register using the *SRE command. For more detail,
see the STATUS command. This bit can only be cleared by sending a *CLS command.
LIM
If a channel pass/fail limit fails, this bit will be set. This bit can be used to set an SRQ by
setting the same bit in the SRE register using the *SRE command. For more detail, see the
STATUS command. This bit can only be cleared by sending a *CLS command.
MAV
If data is available in the output queue, this bit is set. This bit can be used to set an SRQ by
setting the same bit in the SRE register using the *SRE command. This bit is only cleared
when there is no data waiting to be transmitted.
ESB
If any of the event register bits are set and the corresponding event status enable bits are set
the ESB bit in the status byte will be set. This bit can be used to set an SRQ by setting the
same bit in the SRE register using the *SRE command. The ESB bit is cleared when the ESR
is read by using the *ESR? Command.
Figure 8-1. Service Request Status