USB232U/485Ui
Page 11
Figure 3.2 RS232 9-way Port Pin Designations
3.1.3
RS422/485 9-way Port
Connections to the RS485 are made via 9-way D-type connectors on the interface. The on-
board connectors are male and the mating sockets are available as accessories. Provision is
made for securing by screw jacks. The 9-way D-type connector pin-out compatible with the
default pin-out of the Amplicon PCI248H(i)/PCI249H(i) series boards.
Figure 3.3 RS422/485 Amplicon Standard Port Pin Designations
3.2
Connector Wiring for RS422/485 Full/Half Duplex
In the full duplex position, the serial RS422/485 data signals are transmitted on the wire pair
Tx-A (pin 4) and Tx-B (pin 5) and the incoming signals are received on Rx-A' (pin 8) and Rx-B'
(pin 9). In half duplex RS485 operation, the data signals are both transmitted and received on
the two pairs externally wired in parallel.
3.3
The Ground Connections
Each connector is equipped with two or more different ground connections and care must be
taken in the use of these grounds and the cable design to ensure that the EMC requirements
are met, and that isolation integrity is maintained in the case of the devices with isolated
input/output.
The connector pin-out is such that commercially available cables and adapters are normally
usable without modification, but the user must be aware of the requirements to maintain
isolation when the devices at each end are not at nominal earth potential. The choice of
proper, screened cables is also important for the system to maintain Electro-Magnetic
Compatibility.
3.3.1
USB232U Ground Connections
In
full duplex
operation, pins 4 and 5 provide the balanced
Transmitter output, pins 8 and 9 provide the balanced Receiver input
In
half duplex
operation, pins 4 and 5 are linked to pins 8 and 9 via
jumpers JP2 and JP3 to provide transceiver input and output
5
9
4
8
3
7
2
6
1
Received Data - B'
Received Data - A'
Transmitted Data - B
Transmitted Data - A
Reference Ground
PC Chassis Ground
(non-isolated version)
Содержание USB232U
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