Fuji Electric FRENIC-AQUA series User Manual page 27

[ 3 ] Connection with a four-wire host
Although the inverter uses two-wire cables, some hosts adopt only four-wire cables. Connect to
such a host by connecting the driver output with the receiver input with a crossover cable on the
host side to change the wiring method to two-wire.
Four-wire host
(master)
- The driver circuit on the host side must have a function to set the driver output to
high impedance (driver enable: OFF). Though products conforming to RS-485
normally have this function, check the specifications of the host.
- Keep the output of the driver circuit on the host side in the status of high
impedance except when the host is transmitting data (driver enable: OFF).
- Keep the receiver circuit of the host device deactivated (receiver enable: OFF)
while the host is transmitting data to prevent the host from receiving the data it
transmitted. If the receiver cannot be deactivated, program the host so that the
data transmitted by the host is discarded.
Figure 2.7 Connection with a four-wire host
2-12
FRENIC series
[two-wire]