Edwards nEXT240, Instruction Manual

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B800-00-880 Issue A
Page 36 © Edwards Limited 2009. All rights reserved.
Edwards and the Edwards logo are trademarks of Edwards Limited.
Installation
Figure 15 - R S485 multidrop connection
3.7.4 Message structure
The message structure and command set are the same for RS485 and RS232 options. To communicate a message to
the nEXT 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.
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 Section 3.7.7 .
1 RS485 interface on control equipment 2 nEXT pump logic interface