Associated Research OMNIA II 8204, Operation And Service Manual

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7.4.9. GPIB Service Request
The service request capability is not available with the RS-232 interface. The SRQ
line will be activated only after one or more of the service request functions have been
enabled using the Status Byte Enable register command *SRE.
The Status Byte bit assignments are as described in the previous section for status
reporting. When the instrument has requested service, the enabled bit or bits and the
RQS bit 6 will be active or 1. Bits 4, 5, and 7 are not used and will be set to false, or 0
for all Status Byte reads.
After the serial poll (SPOLL) is executed the RQS bit will be cleared to 0 and the
remaining bits will remain unchanged. The Status Byte will not change value until the
Event register is read and cleared for the corresponding Status Byte bit.
For example, after the All Pass SRQ has been enabled, when the test(s) have finished
with pass indications the instrument will set the hardware SRQ line and output the
Status Byte of 41 hex. This means that bit 6 and bit 0 are set to a value of 1. After
reading the Status Byte the Status Byte value will change to 01 hex.
7.5. Non Volatile Memory
The instrument saves or deletes each parameter in non-volatile memory when the file
save "
FS", file save as “FSA”, file new “FN” and file delete “FD” commands are used
to save, create and delete the files. The non-volatile memory has a limited write cycle
life. Therefore, for programmers who wish to send all parameters before executing
each test, the following commands should not be used:
FS
– File Save
FSA
– File Save As
FN
– File New
FD
– File Delete
The parameters will be stored in the CPU's Random Access Memory (RAM) until
another memory location is selected. However, settings written to RAM from
GPIB/USB/RS-232 mode will be lost when power is shut down. Parameter changes
to RAM are unlimited and will not affect the life of the internal non-volatile memory
chip.
A flowchart for an example program is shown on the next page. This flowchart exhibits
how a program could be written to minimize wear to the write life cycle of the non-
volatile memory. First, the “FN” command is used to create a blank file. In this case,
the file is named TEMP. This file is then stored into the memory of the 620L. When the
sequence needs to be recalled, the “FL” (File Load) command is used to recall the
TEMP file. This creates a blank test sequence and steps can be added as necessary.
Then
the steps are added to the file via the “ADD” command and the sequence is
executed. Programming in this fashion, the “FN” command is only used once to create
a sequence. Then that sequence can be constantly loaded with the “FL” command