Page
62
of
73
M-AI-VT-001-EN Rev.C.1
M-AI-VT-001-EN Rev.C.1
Controls Installation
CIM Board RS-485 Cable
Connections
Connect the RS-485 cable to the CIM as follows:
1. Attach the positive (+) polarity wire to the
NETA terminal.
2. Attach the negative (-) polarity wire to the
NETB terminal.
3. Attach the cable ground shield to the COM
terminal.
4. Connect the other end of the RS-485 cable to
the system controller ensuring that the polarity
of the wires matches the polarity at the CIM.
Termination matches impedance of a node
(transmitter/receiver) to the impedance of the
transmission line (cable). When impedances
are mismatched, the transmitted signal is not
completely absorbed by the load and a portion
reflects back into the line.
If the CIM is not physically located at the end
of the RS-485 (Modbus) network, or if it is the
only module in the network, leave the Modbus
termination jumper as installed by default,
see Figure 43 otherwise, remove the jumper
to disable termination resistor. The CIM board
is shipped with the CAN and RS-485 jumpers
installed by default.
RS-485 is a 2-wire bus interface compatible with
multi-drop network topology. Nodes can be
connected as a bus, or via drop cables from a
common trunk line. A total of 32 nodes can be
connected to one network segment; repeaters
divide network segments. Note, each repeater
functions as a node within the segment it is
installed in. Each node connected within a given
network must have a unique node address across
all segments. Terminate each segment at both
ends using either the termination switch (S801)
of the drive modules, or a biased termination
resistor network. Always use screened twisted
pair (STP) cable for bus cabling, and always follow
good common installation practice.
Low-impedance earth connection of the screen
(shield) at every node is important, including at
high frequencies. Thus, connect a large surface
of the screen to earth, e.g. with a cable clamp
or a conductive cable gland. If necessary, apply
potential-equalizing cables to maintain the
same earth potential throughout the network,
particularly in installations with long cables.
To prevent impedance mismatch, always use
the same type of cable throughout the entire
network. When connecting a motor to the
drive module, always use screened (shielded)
motor cable.
CIM Board RS-485 Cable
Termination
RS-485 Installation
and Set-up
Figure 43
Termination Jumper Settings
for Multiple CIM Boards
