Optical Systems Design OSD8327 Series, Operator'S Manual

Page: 11 / 20

OPTICAL SYSTEMS DESIGN
DOC ID: 10116601
OSD8327 OPERATOR MANUAL
PAGE 11
2.2.7
DATA CONNECTIONS
Data signals are connected to the 8-way terminal block connector as set out in Table 3
TABLE 3: DATA CONNECTOR PIN ASSIGNMENTS
8 WAY DATA
TERMINAL BLOCK
FUNCTION
1 GROUND
2 RS232 OUTPUT
3 RS232 INPUT
4 RS422 OUTPUT - / RS485 (4W OUTPUT -)
5 RS422 / RS485 (4W )
6 GROUND
7 RS422 INPUT - / RS485 (2W I/O, 4W INPUT -)
8 RS422 INPUT + / RS485 (2W I/O, 4W INPUT +)
FIGURE 6: DATA CONNECTOR PIN ASSIGNMENTS
RS485 2-Wire
half duplex is used to connect several devices to the same bus when only one unit
transmits data at a time. All units are normally in high impedance receive mode waiting for data. When
transmission of data is requested, the device waits for a protocol specific turn-around time delay before
transmitting after which it returns to receive mode.
RS485 4-Wire
full duplex is used for master/slave arrangement. Devices are polled and respond faster
with no turn-around time delay required between request/response. The receiver is always enabled
allowing the devices to receive data even while responding to a request.
Note:
If a link doesn't seem to be working correctly (no communication or just one way
communication), try swapping the polarity of the data lines on both ends. Some devices are marked
opposite the RS485 standard.
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