Connect The Serial Interface To The Customer Control Equipment - Edwards nEXT730D Instruction Manual

is also a multi-drop mode that allows for the connection of more than one nEXT pump to
a single serial port on the control system.

5.6.1 Connect the serial interface to the customer control equipment

The serial interface is available in RS485 or RS232 options which can be selected using
the slide switch located adjacent to the main power lead.
To adjust the slide switch, toggle the slide switch using a small tool. The motor controller
default setting is RS232 serial interface. Be sure to replace the round seal to ensure the
IP rating of the pump is still achieved.
CAUTION:
When connecting the pump to a PC, note that the 0 V pin on the RS232 connector
may be connected to earth through the PC. If this is the case, ensure that the 0 V rail
of the 48 V d.c. supply is not also connected to earth at some other point such as at
the power supply. If the 0 V rail of the 48 V d.c. supply will not be connected to earth
at the PC, an opto-isolated interface to the PC should be used.
The nEXT pump can connect directly to the RS485 or RS232 serial input on the control
equipment or a PC as shown in
and Figure: Logic interface connections - RS485 serial
is the serial link master and the nEXT pump is the slave. The distance over which the
serial link will work is dependent on any difference in voltage between the 0 V at the
sending and receiving end. If the 0 V reference at the receiving end is within 0.3 V of the
0 V Control Reference pin on the nEXT pump control connector, then the serial link
should be capable of operating at distances up to 6 m. An interface circuit external to
the nEXT pump may be required for longer distances.
The software in the nEXT pump is capable of operating with several pumps connected to
a single serial link master. This is referred to as multi-drop mode. The RS485 option is
recommended for multi-drop mode. With the RS232 option selected, some additional
hardware will be required to link several nEXT pump units to a single serial link master. A
concept drawing of one possible arrangement is shown in
for multi-drop connection using RS232
selected, connecting several nEXT pumps to a single master becomes a simple wiring
exercise as shown in
B8J200880_D
300812671_002_C3
B8J200880_D - Installation
Figure: Logic interface connections - RS232 serial control
interface. Conversely when the RS485 option is
Figure: RS485 multi-drop
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control. In this configuration the PC
Figure: Conceptual diagram
connection.
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