Service Requests; Communication Monitor Menu; Command Descriptions - Ametek 7280 Instruction Manual

6.3.14 Service Requests

6.3.15 Communication Monitor Menu

6.4 Command Descriptions

Bit Status Byte
bit 0 command complete
bit 1 invalid command
bit 2 command parameter error
bit 3 reference unlock
bit 4 overload
bit 5 new ADC values available
after external trigger
bit 6 asserted SRQ
bit 7 data available
The interface defined by the IEEE-488 standard includes a line (pin 10 on the
connector) called the SRQ (service request) line which is used by the instrument to
signal to the controller that urgent attention is required. At the same time that the
instrument asserts the SRQ line, it also asserts bit 6 in the status byte. The controller
responds by executing a serial poll of all the instruments on the bus in turn and
testing bit 6 of the status byte in order to discover which instrument was responsible
for asserting the SRQ line. The status byte of that instrument is then further tested in
order to discover the reason for the service request and to take appropriate action.
In the model 7280 the assertion of the SRQ line is under the control of a byte called
the SRQ mask byte which can be set by the user with the MSK command or via the
GPIB Settings menu. If any bit in the status byte becomes asserted, and the
corresponding bit in the mask byte has a non-zero value, the SRQ line is
automatically asserted. If the value of the mask byte is zero, the SRQ line is never
asserted.
Hence, for example, if the SRQ mask byte is set to 16, a service request would be
generated as soon as an overload occurred; if the SRQ mask byte were set to 0, then
service requests would never be generated.
A most useful feature of the model 7280 when troubleshooting communications
problems is the Communications Monitor menu, which is described in detail in
section 5.3.17. However, once the problem has been resolved it is recommended that
the instrument be reset to Main Display mode to avoid slowing down
communications.
This section lists the commands in logical groups, so that, for example, all commands
associated with setting controls which affect the signal channel are shown together.
Appendix G gives the same list of commands but in alphabetical order.
Chapter 6, COMPUTER OPERATION
Overload Byte
not used
CH1 output overload
CH2 output overload
Y channel output overload
X channel output overload
not used
input overload
reference unlock
6-9