Edwards nEXT200200, Инструкция по эксплуатации

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4.7.6 Multi-drop operation
With multi
‑
drop mode, a single computer system can communicate with more than one
pump. Each pump must be assigned its own individual address before it can be installed
in a multi
‑
drop system. The command to assign the multi
‑
drop address is sent in
standard nEXT message format. Refer to Assigning a multi-drop address on page 61 .
The message protocol in the multi
‑
drop mode is different than the protocol given for the
serial messages in the single pump systems. The differences in the multi
‑
drop message
protocol are:
▪ All multi
‑
drop commands, queries or replies have the first character as
#
.
▪ All commands, queries and replies have a header that has:
▪ the address of the node that the message is to
▪ the address of the node that the message is from
▪ Delimiter character: (colon) which separates the two multi
‑
drop addresses in the
header
▪ The remaining message (command, query or reply) obeys the same protocol as
given for the single pump systems.
▪ The wild card address 99 is useful which means 'any' node.
After a pump has been assigned a multi
‑
drop address, it will ignore the messages in the
format for the single pumps. An individual pump will ignore all the command messages
unless the multi
‑
drop address matches its own address.
4.8 Connection for mixed parallel and serial operation
You can use the parallel interface control inputs to control the pump. At the same time,
you can use the serial interface or the USB service port (using the manufacturer's nST PC
software) to monitor different pump parameters.
Alternatively, you can use the commands sent over the serial interface to control the
pump. At the same time, you can monitor the normal signal and analogue output over
the parallel interface.
Refer to
Figure: Logic interface connection - mixed parallel and serial operation on page
51 for the schematic diagram of a system that demonstrates how to do this. The
connection is a combination of the parallel and serial connection, given in Connect the
parallel control and monitoring on page 40 and Connection for serial control and
monitoring on page 41 . Options given in the sections are available in a mixed parallel
and serial operation.
Note:
While serial enable is active to enable the serial link, the parallel standby and fail signals
are not available.
The multi-drop connection is shown in Connection for serial control and monitoring on
page 41 . You can use the multi
‑
drop connection with mixed parallel and serial operation.
You can use the multi
‑
drop connection with mixed parallel and serial operation.
You cannot use the parallel interfaces and serial interfaces at the same time to control
the pump. For example, if you start the pump by sending a start command over the
serial interface, you cannot stop the pump by using the start or stop switch on the
parallel interface. To stop the pump, send a serial stop command. Only when the serial
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B85200880_D - Installation