5560A/5550A/5540A
Remote Programmers Manual
20
Table 9. IEEE-488 Interface Messages (Received)
Mnemonic Name Function
ATN Attention
A control line that, when asserted, notifies all instruments on
the bus that the next data bytes are an interface message.
When ATN is low, the next data bytes are interpreted as
device-dependent or common commands addressed to a
specific instrument.
DAC Data Accepted Set the handshake signal line NDAC low.
DAV Data Valid Asserts the handshake signal line DAV.
DCL Device Clear Clears the input/output buffers.
END End
A message that occurs when the Controller asserts the EOI
signal line before it sends a byte.
GET
Group Execute
Trigger
Trigger a TC measurement and put the reading in the output
buffer.
GTL Go To Local
Transfer control of the Calibrator from one of the remote
states to one of the local states. (See Table 3)
LLO Local Lockout Transfers remote/local control of the Calibrator. (See Table 3)
IFC Interface Clear A control line that sets the interface to a quiescent state.
MLA
My Listen
Address
Addresses a specific device on the bus as a listener. The
controller sends MLA automatically whenever it directs a
device-dependent or common command to a specific
instrument.
MTA My Talk Address
Addresses a specific device on the bus as a talker. The
controller sends MTA automatically whenever it directs a
device-dependent or common query to a specific instrument.
REN Remote Enable Transfer remote/local control of the Calibrator. (See Table 3)
RFD Ready For Data Set the handshake signal line NRFD low.
SDC
Selected Device
Clear
Does the same as DCL, but only if the Calibrator is currently
addressed as a listener.
SPD Serial Poll Disable Cancels the effect of a Serial Poll Enable.
SPE Serial Poll Enable
After the Calibrator receives this message, it sends the Status
Byte the next it is addressed as a listener, no matter what the
command is.
UNL Unlisten
Unaddresses a specific device on the bus as a listener. The
controller sends UNL automatically after the device has
successfully received a device-dependent or common
command.
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