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3 - COM Ports
Note for Termination
Resistors for COM
1 in RS-485 Mode
Note for Fail-Safe
Resistors for COM
0 in RS-485 Mode
Note for Fail-Safe
Resistors for COM
1 in RS-485 Mode
29 | © 2019 ABB | DOC. N° 1SDH002109A1001 - ECN000125349 - Rev. A
The E-Hub 2.0 provides the following COM ports:
•
1x RS-485: COM 0; Surge protected, Insulated, Half Duplex
•
1x RS-232/485: COM 1; Surge protected, RS-485 termination and fail-safe resistors
(Default: RS-232)
COM ports specifications:
•
The COM ports are surge protected
•
Maximum supported baud rates are:
•
For RS-232 mode: up to 450 kbps
•
For RS-485 mode: up to 1.75 Mbps
The COM connectors are available on the front side.
COM 1 has 2 pairs of pins (each signal is doubled):
•
If the E-Hub 2.0 is located at the beginning, or at the end, of a RS-485 chain, spare pair
of pins can be used to connect permanently standard axial resistor 120 Ohm, if the
application requires that
•
If the E-Hub 2.0 is not at the beginning or at end of the RS-485 chain, two options are
available:
•
Option 1: one pair of pins can remain not connected
•
Option 2: one pair of pins can be used to connect the previous device of the chain,
and the other pair can be used to connect the following device of the chain
Fail-safe resistors (1.21 kΩ) are already inserted by default, and cannot be removed by the
user.
To insert the RS-485 fail-safe resistors, use the DIP switch available in the Service Panel.
Switches meaning
Default DIP switch configuration is OFF; this means no resistors inserted.
Fig. 10
SW #
Signal
1
RS232_RX/485_D+ Line
2
RS232_TX/485_D- Line
Description
ON: 4.7 kΩ pull-up resistor inserted on COM 1
ON: 4.7 kΩ pull-down resistor inserted on COM 1
INTERFACES IN DETAIL | COM Ports
ABB | E-Hub 2.0
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