Ps410 Port 1 To Rs232 Setup; Led Functions; Rs485 Line Conditioning - rotork Pakscan IIE System Manual

11.1.2 PS410 port 1 to RS232 setup

To use the converter to convert the master station RS485 port (Port 1) to a second RS232 port.
Set J1 to positions 1-2, 4-5 and 7-8 (marked 'PORT 1 TO RS232' on the PCB)
Set J2 according to the baud rate being used
Set J7 to positions 1-2 and 7-8 (2-wire mode)
Set jumpers J3, J4, J5 and J6 according to Section 11.1.4
Connect Port 1 and Port 4 together at the back of the rack with a length of cable terminated
in 9-way D-type connectors. Ribbon cable is suitable.
RS232 communications will use the 'Port 3' connector on the back of the rack.
This second RS232 port is isolated, and has the same I/O connections as the master station port 2,
except that the 'CTS' signal is not supported.

11.1.3 LED functions

The top LED comes on when data is being transmitted on the RS485 side. The bottom LED comes on
when data is being received on the RS485 side.

11.1.4 RS485 line conditioning

Proper conditioning of a multi-drop RS485 serial link is essential if it is to work properly. It should
ideally be terminated with about 120 ohms at each end, but NOT at each node, and at one point only
on the link there MUST be 'pull-apart' resistors to bias the line to the idle state when nobody is driving
it. Provision for both data line termination, J4, and 470 ohm pull-apart resistors, J3, is made on the
Converter. Whether or not the jumpers should be fitted depends on the design of the whole system.
Jumpers J5 and J6 carry out similar functions for the RS485 control line.
In practice, some experimentation may be necessary to find the correct setting of these jumpers in
each application. At the baud rates that the master station uses, line termination (J4 and J6) often
does not have much effect, but the 'pull-apart' resistors (J3) are critical to successful communications.
Without the 'pull-apart' function, communications may be subject to many errors or may fail
completely.
If 4-wire mode is selected, J3 and J4 operate on the Transmit lines, and J5 and J6 operate on the
Receive lines.
Fig 18: PS410 Converter bias and termination resistors
85 of 132
+5V
120
J3
Data +
J4
100
Data -
J3
120
Gnd
Publication S177E V2.0 Issue 12/04
PS410 Converter
+5V
120
J5
RTS +
J6
100
RTS -
J5
120
Gnd