9
Analog Input/Output
DO+ and DO–
Together, the voltage output DO+ (Z32)
and DO– (Z30) signals constitute a
differential analog output with a range of
+10 VDC full scale. The output typically
drives a servo. Figure 2-9 shows a
typical connection.
Figure 2-9. Differential Voltage Output
SO and AGND
Together, the AGND (Z28) and SO (Z26)
signals constitute a single-ended analog
output with a range of +10 VDC full
scale. It serves as an alternative
method of connecting the SMC20 to a
drive amplifier, but is more susceptible to
noise than the differential connection.
Therefore, if you use Z28/Z26, use them
only with cable that is shorter than 20
feet.
Use a two-wire shielded cable: Connect
the shield to ground only at the SMC20
end. Do not connect the amplifier end of
the shield to ground. Some installations
may require shield ground at each unit.
Figure 2-10 shows a typical connection.
Figure 2-10. Single Ended Voltage
Output
IN1+ (Z22) and IN1– (Z20)
The Z22 (IN1+) and Z20 (IN1–) signals
constitute analog input Channel 1. This
differential analog input can be used as
a variable. Please refer to the
Programming Reference Manual for use
of this input.
Both connections require twisted pair
shielded cable. Figure 2-11 shows a
typical connection.
Figure 2-11. Analog Input Typical
Connection
Z10 and Z8, Z16 and Z14
These inputs are not used.
IOUT+ (Z6) and IOUT– (Z4)
The IOUT+ and IOUT– signals
constitute an op50 mA current
output for driving a hydraulic servo
valve, or other current driven actuators
or amplifiers. Figure 2-12 shows a
typical connection.
AGND (Z24, Z18, Z12, and Z2) pins
provide analog signal ground.
Figure 2-12. IOUT+ (Z6) and IOUT–
(Z4) Current Output
CAUTION
The
SMC20
controller
can
be
supplied
with
`Active
High'
or
`Active
Low'
digital
I/O.
Determine
which
version
you
have
(from
model
no.
on
label)
and
make
sure
that
external
devices
connected
to
the
controller
are
compatible.
Improper
operation,
damage,
or
personal
injury
can
occur
if
digital
I/O
signals
are
inadvertently
activated.
Digital Inputs:
Figure 2-13. Digital Inputs
An ‘Active High’ input is ‘On’ when input
voltage is > 10 Vdc. An ‘Active Low’
input is ‘On’ when input voltage is < 8
Vdc.
