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5-74
IEEE-STD-488.2
Common
Commands and
Queries
Since most instruments and devices in an ATE system use similar
commands that perform similar functions, the IEEE-STD-488.2
document has specified a common set of commands and queries
that all compatible devices must use. This avoids situations where
devices from various manufacturers use different sets of commands
to enable functions and report status. The IEEE-STD-488.2 treats
common commands and queries as device dependent commands.
For example, *TRG is sent over the bus to trigger the instrument.
Some common commands and queries are optional, but most of
them are mandatory.
The following is a complete listing of all common-commands and
queries, which are used by the 2074
*CLS - Clear the Status Byte summary register and all event registers.
*ESE <enable_value> - Enable bits in the Standard Event enable
register. The selected bits are then reported to the status byte.
*ESE? - Query the Standard Event enable register. The generator
returns a decimal value, which corresponds to the binary-weighted sum
of all bits, set in the register.
*ESR? - Query the Standard Event register. The generator returns a
decimal value, which corresponds to the binary-weighted sum of all
bits, set in the register.
*IDN? -
Query the generator’s identity. The returned data is organized
into four fields, separated by commas. The generator responds with its
manufacturer and model number in the first two fields, and may also
report its serial number and options in fields three and four. If the latter
information is not available, the device must return an ASCII 0 for each.
For example, Model 2074 response to *IDN? is:
Tabor,2074,0,1.01
*OPC - Set the "operation complete" bit (bit 0) in the Standard Event
register after the previous commands have been executed.
*OPC? - Returns "1" to the output buffer after all the previous
commands have been executed. *OPC? is used for synchronization
between a controller and the instrument using the MAV bit in the Status
Byte or a read of the Output Queue. The *OPC? query does not affect
the OPC Event bit in the Standard Event Status Register (ESR).
Reading the response to the
*OPC? query has the advantage of
removing the complication of dealing with service requests and multiple
polls to the instrument. However, both the system bus and the
controller handshake are in a temporary hold-off state while the
controller is waiting to read the *OPC? query response.
*OPT? -
Returns the value “0” for a 2074 with no options.
*RST - Resets the generator to its default state. Default values are
listed in Table 5-1.
*SRE <enable_value> - Enables bits in the Status Byte enable register.
*SRE? - Query the Status Byte enable register. The generator returns