Remote Operation
Using Commands
5
5-29
Table 5-5. IEEE-488 Interface Messages (Sent)
Mnemonic Name Function
END End A message that occurs when the 5520A asserts the EOI control
line. The 5520A asserts EOI while it transmits the ASCII character
LF for its termination sequence or terminator.
DAC Data Accepted Set the handshake signal line NDAC low.
DAV Data Valid Asserts the handshake signal line DAV.
RFD Ready for Data Sets the handshake line NRFD low.
SRQ Service Request A control line that any device on the bus can assert to indicate that
it requires attention. Refer to “Checking 5520A Status” for details.
STB Status Byte The status byte is what the 5520A sends when it responds to a
serial poll (interface message SPE).
5-29. Compound Commands.
A compound command is two or more commands in a single command line. For
example, the following two commands could be entered individually,
OUT 1 V, 60 HZ
OPER
where the Calibrator sources 1 V ac at 60 Hz, and then goes into operate, or they could
be combined into a compound command,
OUT 1 V, 60 HZ ; OPER
using a semi-colon as a separator. Care must be taken when a compound command
includes any of the coupled commands. (See “Coupled Commands.”)
5-30. Coupled Commands
A coupled command refers to two or more commands that appear in a compound
command (see “Compound Commands”) that perform actions that could interfere with
each other causing a fault. Commands in a compound command are separated by using
the ; character. Compound commands using only coupled commands are not order-
dependent.
In Chapter 6, the command graphic
Coupled
x
shows a check for coupled commands.
The coupled commands, excluding scope commands, are:
CUR_POST DBMZ DC_OFFSET HARMONIC OUT WAVE
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