PWM-C Pulse Width Modulation to
Current Transducers
Control Systems
International
®
General
CSI’s Model PWM-C1 and PWM-C2 transducers provide a 4 to
20 mA and 0 to 20 mA output, respectively, proportional to the
duration of the pulse input.
Both the PWM-C1 and PWM-C2 are provided with a simple 3-
wire electrical connection for control, and 2-wire electrical
connection to the controlled device.
Physical Description
The PWM-C1 and PWM-C2 are contained on a single integrated
circuit board with a footprint of 3.25" W
×
4.0" H (8.25
×
10.2 cm), and are designed for panel mounting using the snap-
track mounting rail. Overall mounting dimensions, including
snap track rail, are 3.5" W
×
4.0" H (8.9
×
10.2 cm).
Electrical connections are terminated on a 5-position terminal
strip on the bottom edge of the card for easy access.
Power and clock status is displayed via a green LED. The presence
of a PWM signal from the controller is indicated by a red LED.
The PWM-C transducers may be powered by a 24-volt AC or DC
source to eliminate the requirement for a special transformer or
power supply for a single transducer. Controller pulse inputs
may be created by mechanical dry contacts, solid state open
collector transistors (NPN), or triacs as shown in the wiring
diagram.
Note:
If the controller output providing the pulse width signal
is a UC triac, you must remove resistor R-27 and diode
D-5 as shown in the wiring diagram. If the controller is
an MR or I/SITE I/O triac, only remove R-27.
PWM-C transducers input full range time is user-selectable
between two jumper selectable ranges: 0.1 to 5.2 second pulse
input or 0.1 to 25.6 second pulse input, to provide rapid loop
response time when required.
•
The time base is jumper selectable via a plug-on jumper
labeled J2.
•
An input pulse of less than 0.1-second duration will be
rejected by the transducer and no change will occur in the
output.
The PWM-C transducers internally limit the maximum input
signal to a full scale range of 255 counts, and do not allow wrap-
around on pulses of longer duration than the specified or
selected maximum.
Upon power initialization, the PWM-C transducers force the
output to 0% of scale value until receipt of the first pulse input
from the controller.
Installation Instructions/Precautions
1.
Carefully remove the PWM-C transducer from the anti-
static packing material.
2.
With due caution, remove the transducer assembly from the
snap track.
Note:
Until you are ready to finally mount the transducer in the
snap track it is recommended that the transducer be
replaced in the anti-static packaging to prevent damage.
3.
Mount the snap track in the desired location, making sure
that the screws used to mount the snap-track do not contact
the underside of the transducer.
a.
The transducer may be mounted either horizontally or
vertically without affecting the operation of the unit.
b.
If mounted vertically, you must install a stop at the
bottom edge of the snap-track to prevent vibration
from causing the transducer to migrate out of the snap-
track.
4.
Make all electrical connections with power Off.
