Rockwell Automation T8153 Trusted Communications Interface Adaptor - Manual (Page 9)

Trusted
TM
Communication Interface Adaptor T8153
Issue 12 Apr 10 PD-T8153 9
The Assembly comprises a printed circuit board (PCB) on which the communications ports and socket
SK1 (connector to the Trusted
TM Communications Interface) are mounted. The Assembly is contained
within a metal enclosure and is designed to be clipped onto the appropriate connector at the rear of the
Controller Chassis. A release button is provided to enable the Assembly to be disconnected.
The communications port available at the Assembly are RS232 (one each of full and partial), RS485
(both direct and multi-drop) and Ethernet (10BaseT and 100BaseT).
2.1. RS232 serial ports
There are two connectors available to access the RS232 ports. Bank 1 provides a full RS232
interface. Bank 2 provides a partial RS232 interface with connections limited to TX, RX, RTS and
CTS.
2.2. RS485 serial ports
1. There are eight connectors available to directly access the four RS485 ports. Banks 1 and 2
cannot be used in the RS485 mode if the Trusted TM Communications Interface is configured
for RS232 on these ports.
2. The RS485 ports are provided with two connectors per port. Each port is provided with link
selectable 120R AC termination on both the transmit and receive circuits as shown in the
table below.
3.
Bank Connector 1 Connector 2 TX Term. Link TX/RX Term. Link
1 J4 J5 LK5 LK1
2 J9 J10 LK6 LK2
3 J11 J12 LK7 LK3
4 J13 J14 LK8 LK4
Table 2 Configuration for multiplexed links
1. The AC coupled termination is used so as to reduce the current drawn on the transmission
line during the idle state. The use of two connectors and link selectable termination is to
make the configuration of multiplexed transmission lines simpler. This method also provides
the termination close to the transceivers thus avoiding unnecessary reflections on the line.
2.3. Examples
RS485 Full Duplex Link
This is a point to point 4 wire link. The connections to the Termination Assembly should be to
Connector 1 with the TX/RX Termination link fitted.
RS485 Full Duplex Multiplexed
This is the most complicated system.
If the Termination Assembly is at the start of the multiplexed chain then Connector 1 is used and the
TX/RX Termination link is fitted.
If the Termination Assembly is in the chain then the Connector 1 is used to connect the chain in and
connector 2 is used to wire out to the next device. No links are fitted for this port.