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Connection for serial control and monitoring
A735-01-860 Issue A
3.4 Message structure
The message structure and command set are the same for RS485 and RS232 options. To communicate a message to
the nXDS pump you must send the characters in a specific order. If the message does not conform to the correct
structure it will be ignored and no reply will be sent.
There are two basic types of message sent to the nXDS pump:
A command sending information to the nXDS pump; this is prefixed with a '!' character
A query requesting information from the nXDS pump; this is prefixed with a '?' character
Data is stored and accessed via two memory types within the nXDS Pump:
Non-volatile memory - this provides access to persistent data which is restored after power-cycling; the
prefix 'S' indicates persistent data.
Volatile memory - this provides access to non-persistent data which is NOT restored after power-cycling; the
prefixes 'C' and 'V' indicate non-persistent data.
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, as the stop character
An extended message protocol is used in multi-drop mode, refer to Section 3.7.
3.5 Command set
Table 3 shows a summary of the full set of commands available for controlling and monitoring the nXDS pump.
Table 4 shows the abbreviations that are used to define commands in the following sections and Table 5 shows the
error codes that might be returned.
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