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Wire the gateway as illustrated. Follow all conventional standards for wiring of EIA-485
networks when connecting the Modbus RTU EIA-485 (RS485) network. This includes
use and termination of shield, termination of the network, and grounding.
IMPORTANT: Although EIA-485 (RS485) is thought of as a 2-wire network, you MUST
include a third conductor connected to GND or common at each device so that all
devices are operating at close to the same ground potential. Proper grounding of
equipment should ensure proper operation without the third conductor; however,
proper grounding often cannot be relied upon. If large common mode voltages are
present, you may even need to insert optically isolated repeaters between EIA-485
devices.
Use standard CAT5 cables for Ethernet connections. Use control wire as applicable for
local electrical codes for connecting the 24V (AC or DC) power supply.
Note that in addition to connecting power supply common to a GND terminal, you
must also connect a GND terminal to earth ground in order to ensure proper ESD
protection.
BB3-6101-232
: The standard BB3-6101 Modbus RTU port uses RS-485. The RS-232
version replaces the RS-485 transceiver with an RS-232 transceiver. The NET+/NET-
terminals are replaced by TXD and RXD on the -232 version. TXD is data out from the
BB3-6101-232, and RXD is data in to the gateway. Hardware handshake is not
supported.
A. Hardware Details
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