Fluke 5520A - Page 182

5520A
Operators Manual
5-28
Table 5-4. 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 Sets 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 sending 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 5520A from one of the remote states to one
of the local states. (See Table 5-1)
LLO Local Lockout Transfers remote/local control of the 5520A. (See Table 5-1)
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 5520A. (See Table 5-1.)
RFD Ready For
Data
Sets the handshake signal line NRFD low.
SDC Selected
Device Clear
Does the same thing as DCL, but only if the 5520A is currently
addressed as a listener.
SPD Serial Poll
Disable
Cancels the effect of a Serial Poll Enable.
SPE Serial Poll
Enable
After the 5520A 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.
UNT Untalk “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 query.