Device
and operation
CPC307
C P C 3 0 7 U s e r M a n u a l
53
© 2 0 2 2 F a s t w e l v . 0 0 6
Figure 4.22. a) Pin assignment of the XP15 and XP20 connectors (for module versions older than 4.
х)
In module versions 4.
х
to connect the Rtr terminating resistor to the RX-/RX+ line, a jumper
should be installed to pins 5-6 of the XP15 connector for the COM5 port and/or to pins 5-6
of the XP20 connector for the COM6 port.
It is also possible to connect 680 ohm bias resistors.
To connect a 680 ohm VCC bias resistor to the TX-TX+ line a jumper must be installed to pins 1-2
of the XP15 connector for the COM5 port and/or to pins 1-2 of the XP20 connector for the COM6
port.
To connect a 680 ohm GND bias resistor to the TX-/TX+ line a jumper should be installed to pins
3-4 of the XP15 connector for the COM5 port and/or to pins 3-4 of the XP20 connector for the
COM6 port.
To connect the Rtt terminating resistor to the TX-/TX+ line it is necessary to simultaneously install
2 x jumpers to pins 1-2 and 3-4 of the XP15 connector for the COM5 port and/or to pins 1-2 and 3-
4 of the XP20 connector for the COM6 port.
Figure 4.22. b) Pin assignment of the XP15 and XP20 connectors (for module version 4.
х)
When the RS-485 network state is inactive, all the drivers are set to the third state, therefore all the
nodes are in the receiving mode. Thus, the network state is not defined. If the potential difference
at the receiver inputs RX+ and RX- is less than the thres
hold value of ±200 mV, then the logic level
at the receiver output (RX) will be the value of the last received data bit. Safety bias resistors are
used to ensure proper voltage levels in the inactive state of the network. A 2.2 k
Ω protective bias
XP15 - connection of terminating
resistors for COM5 port,
XP20
– connection of terminating
resistors for COM6 port.
Enabling Rtr for RX-/RX+ lines (COM6)
Enabling Rtt for
ТХ-/ТХ+ lines (COM6)
Enabling Rtr for RX-/RX+ lines (COM5)
Enabling Rtt for TX-/TX+ lines (COM5)
XP15 - connection of terminating/biasing
resistors for COM5 port,
XP20 - connection of terminating/biasing
resistors for COM6.
Enabling Rtr for RX-/RX+ lines (COM6)
Enabling 680 Ohm GND biasing resistor (COM6)
Enabling 680 Ohm VCC biasing resistor (COM6)
Enabling Rtt for TX-/TX+ lines (COM6)
Enabling Rtr for RX-/RX+ lines (COM5)
Enabling 680 Ohm GND biasing resistor (COM5)
Enabling 680 Ohm VCC biasing resistor (COM5)
Enabling Rtt for TX-/TX+ lines (COM5)