DH Instruments PPCK PLUS, Руководство по эксплуатации и обслуживанию

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PPCK+™ Operation and Maintenance Manual
Page 71
©2001 DH Instruments, Inc .
4.3 PROGRAMMING FORMATS
The PPCK+ program message set is downward compatible with the previous PPCK program
message set. It is identical to the PPC2+ program message set with the exception of a few
commands that are not included for PPCK+ because they support PPC2+ functions that PPCK+ does
not include. This message set includes an enhanced program message format to support IEEE Std
488.2 syntax, format, and status reporting. The user must select whether to use either the original
“classic” program message format, or the new “enhanced” program message format. The enhanced
format is recommended when possible, as the classic format is obsolete. Selection can be
accomplished from the front panel (see Section 3.4.4.3) or remotely by using the “MSGFMT”
program message. The default is the classic program message format to allow downward
compatibility with existing host software. The basic commands are similar for both the classic and
enhanced formats, but the usage, syntax, format and status reporting are different.
The PPCK+ enhanced program message format also includes additional common program
messages that are required in every device that complies with the IEEE Std 488.2. These addition
common program messages are covered separately in Section 4.6.1.
4.3.1 CLASSIC PROGRAM MESSAGE FORMAT
The classic program message format is downward compatible with the previous PPCK
program message set. However, several PPCK functions are not supported by PPCK+ and
neither are their corresponding commands (see CFG, DEVICE, DPG, ISO, PPC, HOLD,
TOUT, TS, CONFIG). This format is recommended only if you need downward compatibility
with older PPCK controllers. Each program message sent is also a query. You can only
send one program message to the PPCK+ at time. After sending any program message, you
must wait for the PPCK+ 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 PPCK+. This ensures that
the PPCK+ has completed the program message. Most remote program messages will
return a reply within 500 ms except:
PR, PRR, SR, ATM, RATE: Up to 2.0 seconds to allow a new measurement.
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
This enhanced program message format uses the IEEE Std. 488.2 format, syntax and status
reporting and is recommended for new applications. 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). 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.