Racal Instruments 1257, Руководство пользователя

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1257 User Manual
EADS North America Defense Advanced SCPI Operations 7-17
Test and Services, Inc.
©
2001
enabled, the 1257 pushes an error message onto the system error
queue and asserts the “Execution Error” bit in the
Event Status
Register .
If the 1257 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 .
Using Relay
Verification
The 1257 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 drawers used in the 1257 typically utilizes open-
drain or open-collector drivers. A separate signal between the coil
of each relay and associated driver feeds back into the 1257 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 1257 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 drawers utilizing
open-drain drivers (virtually all 1260-series drawers), the
readback signal will be pulled low by the driver when the
driver is enabled (high or on state). For these types of
drawers, the verification mask should be manually set to the
inverted mode of operation.
2. Issue a verification command for the relays or range of