DH Instruments E-DWT-H, Руководство по эксплуатации и обслуживанию

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E-DWT-H OPERATION AND MAINTENANCE MANUAL
© 2009 DH Instruments, a Fluke Company Page 74
4.2.1.2 COM2
The RPM4-E-DWT COM2 RS232 interface is located on the back of the unit. It
can be used to allow the host computer to communicate with another device
through the RPM4-E-DWT. This allows the user to use one host COM port to
communicate with the RPM4-E-DWT and an additional RS232 device. Refer to
the “
# ” remote program command for details.
COM2 is a 9-pin female DB-9F connector configured as a DTE device. Data is
transmitted out of the RPM4-E-DWT using pin 3, and is received on pin 2. This allows a
normal pin-to-pin DB-9M to DB-9F RS232 cable to be used to connect to a DCE
device.
Handshaking is not required or supported.
Table 13. COM2 DB-9F pin designations
PIN # FUNCTION DESCRIPTION
2 RxD This pin transmits serial data from the RPM4-E-DWT to a
device.
3 TxD This pin accepts serial data from the external device.
4 DTR This pin is Data Terminal Ready (DTR) (held at + 5 V).
5 Grn This pin is the common return for the TxD and RxD signals.
4.3 Programming Formats
RPM4-E-DWT supports two program message formats, the “classic” , and the “enhanced” formats. The
user must select which format to use. Selection can be accomplished from the front panel (see Section
3.9.2.3) or remotely using the “L2” or “L3” program message (see Section 4.4.4). The ”MSGFMT”
command can also be used to select the format, but is not recommended for new designs.
The main difference between the “classic” and “enhanced” formats is that commands that reply a Boolean type
reply a ‘0’ or ‘1’ when in enhanced mode. Classic mode includes the original command in the reply.
Many RPM4-E-DWT classic and enhanced commands are common with DHI PPC Pressure/Controller
Calibrators.
4.3.1 Program Message Format
Each program message sent is also a query. You can only send one program message to
the RPM4-E-DWT at time. The command can be followed with an optional query operator
“?” if desired, but it is not mandatory. After sending any program message, you must wait
for the RPM4-E-DWT 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-E-DWT. This insures
that the RPM4-E-DWT 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. The format for
the enhanced mode is also indicated where needed.