is also a mul-drop mode tha
t allows for the connecon 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 opons 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 seng is RS232 serial interface. Be sure to replace the round seal to ensure the
IP rang of the pump is sll achieved.
CAUTION:
When connecng the pump t
o 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 Figure: Logic interface connecons - RS232 serial control
and Figure: Logic interface connecons - RS485 serial control. In this conguraon the PC
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 dierence 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 operang at distances up to 6 m. An interface circuit external to
the nEXT pump may be required for longer distances.
The soware in the nEXT pump is capable of operang with several pumps connected to
a single serial link master. This is referred to as mul-drop mode. The RS485 opon is
recommended for mul-drop mode. With the RS232 opon selected, some addional
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 Figure: Conceptual diagram
for mul-drop connecon using RS232 interface. Conversely when the RS485 opon is
selected, connecng several nEXT pumps to a single master becomes a simple wiring
exercise as shown in Figure: RS485 mul-drop connecon.
08/2021 - ©Edwards Limited
Page 60B8J200880_D
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