Racal Instruments 1256E, Руководство пользователя

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1256E User Manual
Racal Instruments
©
2002 Advanced SCPI Operations 8-19
If any relay is not in the correct state and Confidence Mode is
enabled, the 1256 pushes an error message onto the system error
queue and asserts the “Execution Error” bit in the
Event Status
Register .
If the 1256 is accessed through the GPIB interface, this condition
can further be made to generate an SRQ interrupt. This is
accomplished by writing a “1” into the “Execution Error” mask bit of
the
Standard Event Status Register and a “1” into the “ESB” mask
bit of the Service Request Enable Register .
When Confidence Mode is enabled, commands are executed more
slowly because of the time consumed in reading the status of all
relays. The amount of slowdown depends on the quantity and
types of switch modules that are installed.
Using Relay
Verification
The 1256 system also supports the ability to verify that a switch or
a range of switches is closed or open. The syntax for these
commands is shown below:
[:ROUTe]
:VERify
:ALL?
:MASK <channel list>, 0 | 1 | X
:MASK? <channel list>
The 1260 line of switching cards used in the 1256 typically utilizes
open-drain or open-collector drivers. A separate signal between
the coil of each relay and associated driver feeds back into the
1256 for verification and confidence mode checks.
Verification is somewhat different than confidence mode which is
enabled with the MONITOR:STATE command. With confidence
mode enabled, the 1256 verifies the state of all relays in a system
against expectations after performing any relay state changes (i.e.
open or close commands). The result of this test is a high-level
“pass” or “fail” indication for the entire system. Confidence mode
therefore has the ability to quickly test a system, but it is unable to
resolve or identify the exact cause of the failure if one is detected.
Unlike confidence mode, relay verification can be initiated by the
user on a channel by channel basis and can be performed at
anytime (not just at relay state changes). To be able to perform
relay verification properly, several steps need to be performed:
1. Set the proper verification mask indicating whether the
readback channel is normal, inverted, or don’t care. A
channel’s mask defaults to don’t care. For relay cards