Datasheet

TMCC160 motionCookie™ (Rev. 1.00 / 2015-Nov-16)
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The network topology should follow a bus structure as closely as possible. That
is, the connection between each node and the bus itself should be as short as
possible. Basically, it should be short compared to the length of the bus.
Especially for longer busses and/or multiple nodes connected to the bus and/or
high communication speeds, the bus should be properly terminated at both
ends. Therefore, a 120 Ohm termination resistors at both ends of the bus have
to be added.
Avoid floating bus lines while neither the host/master nor one of the slaves along
the bus line is transmitting data (all bus nodes switched to receive mode).
Floating bus lines may lead to communication errors. In order to ensure valid
signals on the bus it is recommended to use a resistor network connecting both
bus lines in order to define logic levels appropriately.
Two configuration options can be recommended. They are explained on the next
page.
Add resistor (Bias) network on one side of the bus, only (120R termination
resistor still at both ends):
Or add resistor (bias) network at both ends of the bus (like Profibus™
termination):
4.6.3
RS485 Bus
Structure
c:>
node
1
node
n
- 1
node
n
Host
Slave Slave Slave
RS485
termination
resistor
(120 Ohm)
termination
resistor
(120 Ohm)
}
keep distance as
short as possible
Figure 16: RS485 Bus Interface Structure
4.6.4
RS485 Bus
Termination
4.6.5
No Floating Bus
Lines
Configuration
Option 1
node
n - 1
node
n
Slave Slave
termination
resistor
(120R)
+5V
GND
pull-up (680R)
pull-down (680R)
RS485- / RS485B
termination
resistor
(220R)
RS485+ / RS485A
Bus lines with resistor (Bias) network on one side, only
Configuration
Option 2