RS232 & GPIB INTERFACE
48
detected that an enabled SRQ has been met and therfore has requested service.
Bit 4,5, and 7 are not used and will be set to false or 0 for all status reads.
After the status byte has been read from the instrument the RQS bit will be
cleared to 0 and the remaining bits will be unchanged. The remaining bit will be
unchanged until the next time service is requested.
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 and
remain at 01 hex until next time service is requested.
12.9 Example of Communicating Over the GPIB bus
To write commands over the GPIB
bus you must enter the code that is specific to
the software language you are using. Then follow the example below:
To set the High Current Trip across the GPIB
bus at 1000
µ
A do the following.
First select the memory and step that you wish to change Then send the string
“SC 1000”
: This tells the instrument to set the High Current Trip to 1000
µ
A. A
string is a list of ASCII characters, octal or hex bytes or special symbols, enclosed
in double quotes.
If you wish to set the Delay time of the test across the GPIB
bus at 10 seconds, do
the following, send the string
“ST 10.00”
. This tells the instrument to set the
Delay Time at 10.00 seconds for the Memory and step that has been selected.
To read the 2 x 20 display, first send the string
“?K”
then send the GPIB
command to read 40 bytes. The instrument will send 40 bytes, one byte for each
character on the display, including spaces.
12.10 Non Volatile Memory
The instrument saves each parameter in non-volatile memory when the parameter
is changed. The non-volatile memory has a limited write cycle life, therefore there
is a special volatile memory location that is available for programmers who wish
to send all parameters before executing each test. Memory 9, step 8 is the
memory location that will
NOT
write the parameter to non-volatile memory.
Settings written to this location from GPIB mode will be lost when power is shut
down. Parameter changes to this location is unlimited and will not effect the life
of the internal non-volatile memory chip.
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