Interface Circuit - Furuno FS-1570 Service Manual

5.3.4 Interface circuit

Table 5.3.7 lists the ports on the transceiver unit.
Port Name
TD1-A, TD1-B
CONTROLLER-1
RD1-A, RD1-B
TD1-A, TD1-B
CONTROLLER-2
RD1-A, RD1-B
SD
RD
REMOTE
TD (MIF-A, MIF-B)
(MIF)
RD (MIF-R)
TD (IEC-A, IEC-B)
IEC
RD (IEC-R)
TD (DMC-A, DMC-B)
RD (DMC-R)
DMC
TD (DMC-A, DMC-B)
RD (DMC-R)
BZ OUT,
RCV BZ
BZ IN, BZ CTR
RS-232C
The RS-232C signals, asynchronous data are represented by voltage levels with respect
to a system common. The data is bi-polar: a +3 to +12 volt indicates an ON (space)
condition while a –3 V to –12 volt indicates an OFF (Mark) condition. The "dead area"
between +3 V and –3 V is designed to absorb line noise.
The 15 m limitation of cable length can be stretched to about 30 m for ordinary cable, if
well screened and grounded, and about 100 m if the cable is low capacitance as well.
RS-422
RS-422 is a balanced interface. A pair of wires is used to carry each signal. The data is
encoded and decoded as a differential voltage between sender and receiver. A typical
truth table for a balanced interface is as follows:
VA-VB < -0.2 V=0, VA-VB > +0.2 V=1
If lines A and B are close together, they will be affected almost identically by external
electromagnetic noise. If the lines are also twisted together, then neither line is
permanently closer to a noise source than the other. Hence the well known "twisted
pair" is extremely effective in eliminating noise from the signal. The output signal level
swings between 0 to +5 V. The RS-422 is designed for greater distance and higher baud
rates than RS-232C.
Signal Name I/F Type
RS-485
RS-485
RS-232C
RS-422
RS-422
C.Loop
RS-422
RS-422
C.Loop
RS-422
RS-422
C.Loop
C.Loop
C.Loop
RS-422
C.Loop
5-19
5.3 T-CPU board (05P0732)
Table 5.3.7 Ports on transceiver unit
Dip switch
-
-
S3-#1/2 OFF
S3-#3/4 ON
-S3-#1/2
ON
Selectable with S2-#3
ON: RS-422
-S3-#3/4
OFF: C.Loop,
OFF
Selectable with S2-#1
OFF: C.Loop,
ON: RS-422
Selectable with
S6: all ON
S2-#2
S7: all OFF
OFF: C.Loop,
ON: RS-422
S6: all OFF, S7: all ON
S4: all OFF, S5: all ON
S4: all ON, S5: all OFF
Connection
Case 1
Case2
DMC
IC-302-DSC
IC-xxx
IC-303-DSC