B722-40-880 Issue F
Page 28 © Edwards Limited 2013. All rights reserved.
Edwards and the Edwards logo are trademarks of Edwards Limited.
Installation
3.7.2 Serial enable
To send a Serial message, first activate Serial Enable. This is achieved by linking the Serial Enable input signal (pin
5) to pin 2 of the customer logic interface mating half. Edwards recommends incorporating this link into the customer
Serial communications cable so that Serial Enable is only activated when the serial cable is connected. When the
cable is removed, Serial Enable will become inactive.
Serial Enable acts as an interlock for commands sent over the Serial Interface. If the pump is running (having been
sent a Serial Start command) and the Serial Enable subsequently becomes inactive, the pump will trigger a fail
condition and will decelerate to rest. To clear this fail condition, re-activate the Serial Enable and send a Serial Stop
command.
3.7.3 Serial protocol
The Serial Interface link is set to 9600 Baud, 8 bits, 1 stop, no parity with no handshaking. The commands are made
up from printing ASCII characters. The maximum message size that can be sent is 80 characters, including start and
end characters.
Note: All alphabetical characters must be sent in upper case format.
Every complete command message sent will receive a response - either a status code or a data return. The DX pump
can only deal with one message at a time. It will only accept a new message once the response to the previous
message has been returned.
If the DX pump receives characters that are not framed inside start and stop characters, it will ignore them. Messages
with the stop character missing will be discarded with no response when a new start character is received. If the DX
pump receives an unrecognisable message between the start and stop characters, it will return an appropriate error
message.
Refer to Section 3.7.7 for more information about operating the DX pumps in multi-drop mode.
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