5.a RS-232/485 COMMUNICATIONS
5.a.1 RS-232/485 OUTPUTS:
CHN AND DMP COMMANDS
A 3500 Series instrument will issue output from its RS-232/485 Interface Port in
response to
• a command to "PRINT" from the front-panel PRINT button or the rear logic I/O
connector (when the interface is in RS-232 mode);
•a CHANNEL (CHN) or DUMP (DMP) command received through the Inter-
face Port (in either RS-232 or RS-485 mode);
• a valid interrogation command received through that port (in RS-232 mode),
or
• any valid or invalid command received through that port (in RS-485 mode).
For the initiation of RS-232 PRINT transmissions, see Section 5.d, below. For pos-
sible responses to mnemonic commands, see Appendix B.
The general form of the CHANNEL (CHN) command is
CHN [CMT]
where [CMT] is the "COMMAND TERMINATOR" (that is, the INPUT TERMINATOR
character which the 3500 instrument has been set to recognize—see Section
3.a.3). This command instructs the unit to transmit the current data for its single
measurement channel from the RS-232/485 Interface Port, in the format selected
by the user.
The general form of the DUMP (DMP) command is
DMP [CMT]
This command is functionally identical to the CHN command.
5.a.2 DATA-TRANSMISSION FORMAT
The data transmitted when the 3500 instrument is instructed to "PRINT" (in RS-232
mode) or when a CHANNEL (CHN) or DUMP (DMP) command has been
received through the RS-232/485 Interface Port (in either RS-232 or RS-485
mode) can include
a. An optional "HEADER" string defined by a LABEL (LBL) command of
LBL=$ [CMT]
where "$" is a string of up to eight characters, including spaces.* The data
"label" is typically a channel name or description (e.g., CHAN 4, INPUT 7, TEST
R, etc.). It has no numeric effect on measurement scaling.
b. An optional NODE-NUMBER "ECHO," if so indicated by the user during the
PRINT button setup procedure (Section 3.a.10) or by application of an ECHO
(ECO) command of
ECO=ON [CMT]
5.1
RUN-TIME OPERATION
5
5.a RS-232/485 COMMUNICATIONS
* To remove an existing LBL string from the transmission, just command LBL=N/A [CMT].
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