B722-40-880 Issue H
Page 26
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Installation
Figure 8 - Conceptual diagram for multi-drop connection
3.7.4
Message structure
To communicate a message to the DX pump, the characters must be sent in a specific order. If the message does not
conform to the correct structure, it will be ignored and no reply will be sent.
The correct structure to use is as follows:
a valid start character, either a '!' character for a store operation or a '?' character for a query operation,
followed by
a command, which will be an upper case alphabetical character, followed by
an object number, comprising three decimal digits, followed by
for some commands only, a data field, comprising a sequence of characters separated from the object
number by a space, followed by
a terminating carriage return
The message protocol in multi-drop mode is marginally different, refer to
.
1. RS232 interface on control equipment
2. Buffer
3. DX pump
4. OR gate
