Instruction manual

To read the Status Byte Summary Register, send the IEEE-488 Serial Poll Mes-

sage. Querying the Summary Register will return a Decimal value, which corresponds,

to the binary - weighted sum of the bits, set in the register. Serial Poll will automatically

clear the “ REQUEST SERVICE “ bit in the Status Byte Summary Register. No other

bits are affected. Performing a Serial Poll will not affect the instrument functioning.

USING SERVICE REQUEST (SRQ) AND SERIAL POLL

For example when the Self-Test is performed on this instrument using the com-

mand *TST? (using the IEEE-488 Remote interface ), it takes time for the instrument

to conduct the test and report the results to the BUS controller. The response will be

given at the end of the Self-Test. Here user may have to keep reading from the Output

Buffer of the instrument to know the result. But by using the SRQ function one can do

this task in a better way as explained below. :

1) Enable your BUS controller’s SRQ interrupt.

2) Enable the SRQ reason “MAV” (Message Available Bit) in the Status Byte Regis-

ter by sending the command as *SRE 16.

3) Send the command *TST? from remote for the Self-Test.

4) Wait till your BUS Controller detects an SRQ on the bus.

5) When an SRQ is detected, poll the SRQ from this instrument to read the SRQ

response message as 80 (50 Hex). This means that the RQS bit is set and the

MAV bit is set in the Status Byte Summary Register.

6) Now read the Output Buffer of the instrument from your BUS controller to get the

Response Message of the Self-Test, which will be a 3 digit decimal number like

620 or 603 and so on.

This unit provides complete SRQ function. When the Controller polls the SRQ

Message, it is found that in case of some Controllers that this Response byte gets

latched in the Controller’s Data-out buffer causing addition of an extra character in the

next message which is read against some query command. So it is advisable to give

a Listen to the Controller Chip with sufficient time-out to flush out such character pend-

ing, if any.

6.11 ERROR MESSAGES AND REPORTING

This section explains in short the Error Messages, which are stored in the

ERROR QUEUE. and are reported when read through the SYSTem:ERRor? . The

messages are stored when query command syntax or hardware errors have been

detected. A record of up to 6 errors is stored in the instrument’s error queue. Errors

are retrieved in first-in-first-out (FIFO) order.