P A G E 20
P I C P L C 1 6 v 7 a
U s e r M a n u a l
MODULES
RELAYS AND OPTOCOUPLERS
Industrial devices usually utilize more power than the
microcontroller can provide via its I/O ports. To enable
the microcontroller to be connected to such devices, the
development system is provided with 16 relays by means of
which it is possible to provide up to 250V/16A power supply.
Each relay has one normally-open (W0, W1...) and one normally-
closed (NW0, NW1...) contact. Sixteen relays are divided in four
groups each consisting of four relays. Relays of one group are
connected to one common contact. Accordingly, there are
COMA, COMB, COMC and COMD common contacts.
In addition to relays, the development system also features
optocouplers, the function of which is to galvanically isolate
signals brought to the microcontroller inputs from industrial
devices. Isolated digital inputs are designed specifically as
digital input receivers for programmable logic control (PLC),
motor control and grid applications to interface between
field-side inputs and a host controller. Input voltage is 5V,
and optocouplers are also linked to one common connector
OCVCC.
Figure 12: Relay Control view
Figure 12: Isolated Input view
Two eight-pole DIP switches marked as SW4
and SW5 are used to connect the MCU pins to
the relay control circuitry:
EIGHT-POLE DIP SWITCHES
Two eight-pole DIP switches marked as SW2 and
SW3 are used to connect the MCU pins to the
optocoupler circuitry:
ON(right):
MCU pins are
connected to the relay control
circuitry
OFF(left):
MCU pins are not
connected to the relay control
circuitry
ON(right):
MCU pins are
connected to the optocoupler
circuitry
OFF(left):
MCU pins are not
connected to the optocoupler
circuitry
