4. REMOTE OPERATION
Page 75 © 2007 DH Instruments, a Fluke Company
4.3.1 CLASSIC PROGRAM MESSAGE FORMAT
Each program message sent is also a query. You can only send one program message to
the RPM4 at time. After sending any program message, you must wait for the RPM4 to reply
before sending another program message. This reply will contain data, or a numeric error
message if the program message was invalid. You must wait for this reply before issuing
another program message to the RPM4. This insures that the RPM4 has completed the
program message. Most remote program messages will return a reply within 500 ms except:
“PR?”, “PRR?”, “SR?”, “ATM?”, “RATE?”: Up to 2 seconds.
“RPT”, “ARANGE”, “AUTOZERO=RUN”: Up to 3 seconds
The syntax and format used for each program message in the classic mode is listed next to
the keyword “Classic”’ in each program message summary in Section 4.4.4.
4.3.2 ENHANCED PROGRAM MESSAGE FORMAT
The enhanced program message format uses the IEEE Std. 488.2 format, syntax and status
reporting. Errors are reported using the IEEE Std. 488.2 status reporting model. If an error is
reported, the error is put into an Error Queue and the “ERR?” query program message can
be used to get a text description of the most recent error. If you are using the IEEE-488 port,
the service request line can be setup to be asserted if this occurs (see Section 4.5.2). In the
enhanced format, there are two possible program message types for every program
message. Each of these two types starts with the same basic text referred to as the program
message header. The two types are COMMAND type and QUERY type commands.

4.3.2.1 USING COMMAND TYPE COMMANDS

Enhanced format commands DO NOT reply when using the IEEE-488 interface
unless a “?” is included in the command. Do not expect a response from the RPM4’s
IEEE-488 interface to non-query (no “?”) commands as there is none. Remote
software will time-out waiting for a response from RPM4. However, in RS232
communications, there is always a response and the response MUST be read prior to
issuing another command.
The COMMAND type of program message executes a process and can
additionally send data to the RPM4 in the form of comma delimited arguments.
This data is usually a setting of some sort that is stored in the RPM4. If data is
specified, it must be preceded by at least one white space from the program
message header and be within the range and format described in the program
message description. The keyword “Command:” appears to the left of the
required syntax in each program message description in Section 4.4.4.
If you are using the IEEE-488 port, the Command type does not generate a reply
unless you place a query operator “?” immediately after the command. You also
may send multiple program messages at once by separating each program
message with a semicolon. The commands are queued and executed in as
received order after the entire message stream has been received, so care in
determining order of execution is needed.
If you are using the RS232 port COM1, the Command type will always generate
a reply so you must wait for a reply before issuing another program message.
Because of this, you can only send one Command program message at a time
while using the COM1 port.