DH Instruments PPCH-G, Руководство по эксплуатации и обслуживанию

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4. REMOTE OPERATION
Page 89 © 2007 DH Instruments, a Fluke Company
4.3.1 CLASSIC PROGRAM MESSAGE FORMAT
The classic program message format is compatible with the PPC3 program message set.
However, several PPC3 functions are not supported by PPCH-G and neither are their
corresponding commands (these include “AUTOVAC”, “AUTOPURGE”, “CONFIG”, “NVENT”, “VAC”,
“TOUT”, and “VALVE”). The classic format is recommended if you need downward compatibility
with older DHI controllers or if you are not going to use the IEEE 488.2 status system.
Each program message sent is also a query. You can only send one program message to the
PPCH-G at time. After sending any program message, you must wait for the PPCH-G 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 PPCH-G. This insures that the PPCH-G has
completed the program message. Most remote program messages will return a reply within
500 ms except:
“PR”
,
“PRR”
,
“SR”
,
“ATM”
,
“RATE”
: 2 seconds to allow a new measurement.
“RPT”
,
“ARANGE”
: Up to 10 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 PPCH-G to non-
query (no “?”) commands, as there is none. Remote software will time-out waiting for a
response from PPCH-G. 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 PPCH-G in the form of comma delimited arguments.
This data is usually a setting of some sort that is stored in the PPCH-G. 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