H 7 - 1
Chapter 7 Digital Output (DO) Circuit
The digital outputs of FB
S
-PLC are available in the following two structures: the 5VDC ultra high speed Line-driver type
differential output (i.e., one output occupying two terminals), and the single-end output circuit for saving terminals.
There are three kinds of output device for the single-end output, which are relays, TRIAC and transistors. Since the
relay and TRIAC are bilateral, even when used in single-end output, they can serve as SINK or SOURCE output. The
transistor, however, because of its polarities, after being used as single-end common output, its SINK and SOURCE
polarities are exactly the opposite (common point Cn of SINK output must connect to negative end of DC power).
Therefore, the product model of transistor output of FB
S
-PLC for SINK and SOURCE is distinct. At the right side of
terminal block of FB
S
-PLC, there is a place for making SINK or SOURCE label.
Warning
No over current protection is available in the FB
S
series PLC. Except for the 5V differential output circuit, all
other output circuits have to be added with over current or short circuit protections externally, such as fuses,
in applications with safety concern.
Terminals labeled by
〝●〞
on the terminal block are empty contacts, which cannot be connected with any wire
to maintain the required safety clearance and to avoid damage to the unit.
In situations where simultaneous operations of outputs(such as reverse/forward action of motor) pose safety
concerns, besides the interlock in PLC programs, additional interlock circuits are needed outside PLC, as
shown below
：
輸出
PLC
反轉輸出
輸出
反轉極
限開關
PLC
正轉輸出
正轉極
限開關
電磁開關或
繼電器B
電磁開關或
繼電器A
互鎖接點
(NC)
互鎖接點
(NC)
Output
PLC
Forward
output
Forward
limit switch
Magnetic
switch or
Relay A
Interlock
contact
(NC)
PLC
Reverse
output
Reverse
Limit
switch
Interlock
contact
(NC)
Magnetic
switch or
Relay B
Output
