PF2100 4-20mA Input Card User Manual v1.2
©2021 Profire Energy Inc
June 2, 2021
Page 11
Connecting the “Level”
Current Loop Using an External Power Source
If
after consulting the “
” section of this document you have determined that it is necessary to
use an External Power Source, then wire the pluggable header according to Figure 11.
Connecting the “Level” Status Contac
ts
The “NO” (normally open) contact is closed (connected to the “COM” pin)
when the level input is below the
high setpoint and
is open (not connected to the “COM” pin)
when it is equal to or greater than the high
setpoint. A common use for this contact is to control a pump that is designed to pump liquid into the tank
until it is full.
The “NC” (normally closed) contact always has the opposite status of the “NO” contact.
A common use for
this contact is to turn on an indicator light or send a signal to a remote location when the tank becomes full.
Figure 12 shows an example of how to wire the contacts to a pump and indicator lamp as
described above.
IMPORTANT: Be sure that you do not exceed the current rating of the contacts with whatever
equipment you hook up. Use relays if you need to switch higher power devices.
Contact
PF2100 Powered
Off
PF2100 On and
Level < High Trip
PF2100 On and
Level >= High
Trip
NO
Contact Open
Pump Off
Contact Closed
Pump On*
Contact Open
Pump Off
NC
Contact Closed
Lamp On*
Contact Open
Lamp Off
Contact Closed
Lamp On*
*Assumes Power to AC Voltage Source shown in figure 12 is still on.
Figure 11
Figure 12
