28 29 30
A/+
B/-
28 29 30
PE
120
Ω
max. 1200m
Figure 8: Typical wiring of the RS-485 communication line terminals in SMY 133 .
12÷24
VDC
Other Instrument
max.
5mA
L
N
250VAC/5A
max
Relay
Output
Pulse
Output
Input
12÷48
VDC
Other Instrument
Pulse
Input
max.
60VDC
100mA
Figure 9: An example of wiring connection for inputs and outputs in SMY 133 .
2.2.5
Outputs and inputs
Instruments can be equipped with optional outputs and inputs. Two digital outputs DO1, DO2 (electromechan-
ical relay or solid-state according to the option), one digital input DI1 and two virtual programmable alarms A1
and A2 are available in the instrument. Outputs are connected to the terminal no. 15 to 18 on the rear panel of
an instrument. Input signal can be connected to terminal nr. 19 and 20. A cable maximum cross section area
is 2
.
5
mm
2
. Both inputs and outputs are isolated from the instrument internal circuits as well as between each
other.
Digital outputs DO1 and DO2 (optional with RR, RI and II)
can be configured to generate pulses
from an electricity meter or other quantity, as a simple programmable two-position controller or as a remote
application controlled output.
Relay output (R)
(SPST-NO: single-pole, single-throw, normally open relay) is used. Maximum allowable
voltage and load current according to the technical specifications must be fulfilled.
Impulse output (I)
is accomplished by a semiconductor switching device. It is assumed that the input opto-
couplers of the external recording or control system will be connected to these outputs via proper current–limiting
resistors. The signal polarity is not significant to the device.
10
