GE 90-30 PLC Series Installation And Hardware Manual page 371

HOST
COMPUTER
TERMINATION RESISTANCE FOR THE RECEIVE DATA (RD) SIGNAL NEEDS TO BE CONNECTED ONLY ON UNITS AT THE END OF THE LINES.
*
THIS TERMINATION IS MADE ON THE SERIES 90 PLC PRODUCTS BY CONNECTING A JUMPER BETWEEN PIN 9 AND PIN 10 INSIDE THE
15-PIN D-SHELL WITH THE FOLLOWING EXCEPTION. FOR SERIES 90-70 PLCs, CATALOG NUMBERS IC697CPU731 AND IC697CPU771,
THE TERMINATION FOR RD AT THE PLC IS IMPLEMENTED BY A JUMPER BETWEEN PIN 9 AND PIN 11.
Figure C-3. Example RS-422 Isolated Repeater/RS-232 Converter Connection
System Configurations
The figures below show various ways you can connect the Isolated Repeater/Converter to convert
signals, expand the number of drops, and obtain greater distance. Any system configuration can be
reduced to a minimum number of cables each covering a part of the overall system configuration.
The following examples of system configurations refer to these cables as Cables A through E
which are described in Cable Diagrams later in this section.
Downstream and Upstream Contention. In this section, simple multidrop configurations are
those where a single Isolated Repeater/Converter is used. Complex multidrop configurations
contain one or more multidrop sections where an Isolated Repeater/Converter is included as one
of the drops. In both simple and complex multidrop configurations, the transmitters directed
downstream from the master can be on at all times. There will be no contention for the
communication line because only one device (the master) transmits downstream.
In simple multidrop configurations, there will be no contention when transmitting upstream as long
as devices tri-state their drivers when idle and turn them on only when they have something to
transmit. This is the case for the Series 90-70 and Series 90-30 CMMs.
In complex multidrop configurations, however, special steps must be taken to switch the upstream
transmitters of the Isolated Repeater/Converter.
Switching Upstream Transmitters. For the RS-422 drivers to be active at the J2 port of the
Isolated Repeater/Converter, the RTS input at J must be true. The state of the RS-422 drivers at
the J port depends on the position of the switch on the unit. When the switch is in the center
position, the J transmitters will always be turned on. When the switch is in the CTS position,
(toward the power cable), then either the RS-232 or RS-422 CTS signal must be true to turn on the
J drivers.
Note:
GFK-0356Q Appendix C IC655CCM690 Isolated Repeater/Converter
RS-232 RS-422 ISOLATED REPEATER
SHIELDED RS-232 CONVERTER
PAIRS (IC655CCM590)
PIN PIN
TD 3 RD
RD 2 SD
RTS 5 CTS
CTS 4 RTS
DCD 7 GND
DTR
GND
25-PIN 25-PIN
MALE FEMALE
RS-232/
RS-422
PORT
115VAC
Note the position of the switch on the Isolated/Repeater Converter in the system
configurations below.
IC655CCM590 Converter
RS-422
TWISTED SHIELDED
PAIRS
J2 J1
PIN
150 Ω
RD (B') 22
RD ( A' )
**
RD (A') 23
RD ( B' )
SD ( A )
15
SD ( B )
14
CTS ( A' )
16
CTS ( B' )
17
RTS ( A )
11
RTS ( B )
10
13
12
7
0V
25-PIN 25- PIN
FEMALE MALE
RS-422
PORT
** SWITCH IN CENTER POSITION
C
a44783
PIN
2 SD ( A )
3 SD ( B )
12 RD ( A' )
13 RD ( B' )
10 RT
SERIES
11 RTS ( A )
90 PLC
9 RTS ( B )
RS-422
*
6 CTS ( A' )
PORT
14 CTS ( B' )
15 0V
8 SHLD
7
1
15- PIN 15- PIN
MALE FEMALE
C-5