Manual
©Copyright 2012 Dwyer Instruments, Inc. Printed in U.S.A. 11/12 FR# M1-443559-00 Rev. 6
MERCOID DIVISION
DWYER INSTRUMENTS, INC.
P.O. BOX 258 • MICHIGAN CITY, IN 46360 U.S. A.
Phone: 219/879-8000 www.dwyer-inst.com
Fax: 219/872-9057 e-mail: info@dwyer-inst.com
SETUP & CALIBRATION
Two  multi-function  buttons  are  provided  for  all  calibration  operations.
With these you can set the zero and span points, adjust the 4 and 20 mA
calibration  points,  or  reset  the  4  and  20  mA  calibration  points  to  the
factory settings. All settings are stored in nonvolatile memory so they will
not be lost if the power is removed. 
Zero and Span Calibration
The  zero  and  span  calibration  is  done  with  the  CRF2  installed  in  the
measured tank or vessel. Calibrating zero or span can be done in either
order as these settings are independent of one another. The calibration
can be done such that the output can go from 4 to 20 mA or from 20 to
4  mA  depending  on  the  desired  measurement  for  full  and  empty
conditions.
The  span  or  zero  calibration  is  activated  by  pressing  and  holding  the
corresponding ˝Zero˝  or  ˝Span˝  button for  three  seconds. Set the  tank
level to one endpoint (i.e., full or empty), then press and hold either the
Zero or Span button corresponding to the desired endpoint. Set the tank
to  the  other  endpoint  then  press  and  hold  the  opposite  Span  or  Zero
button. Calibration is now complete. 
NOTE: Be  careful  to  press  the  buttons  only  once  within  3  seconds.
Double  clicking the  switches within  3 seconds  will place  the unit  in
current  calibration  mode.  If  this  happens  press  both  buttons
simultaneously to exit the current calibration mode. If the calibration was
accidentally  changed,  the  factory  calibration  can  be  restored  as
described later in ˝Restore Factory Calibration˝.
Current Calibration
The 4 and 20 mA points of the CRF2 have been calibrated at the factory
and generally will not need to be recalibrated, but if needed the points
may be recalibrated. To do this you will need a milliammeter connected
in the current loop. 
To  calibrate  the  4  mA  calibration  point,  ˝double  click˝  the  Zero/4  mA
button  by  pressing  it  twice  within  1.5  seconds.  The  milliammeter  will
indicate approximately 4.00 mA. Adjust the 4 mA set point by pressing
the Zero/4 mA button to decrease the current and the Span/20 mA button
to increase the current. When complete, press both the Zero/4 mA and
Span/20 mA buttons simultaneously to exit the calibration mode. 
To calibrate the 20 mA calibration point, ˝double click˝ the Span/20 mA
button  by  pressing  it  twice  within  1.5  seconds.  The  milliammeter  will
indicate approximately 20.00 mA. Adjust the 20 mA set point by pressing
the Zero/4 mA button to decrease the current and the Span/20 mA button
to increase the current. When complete, press both the Zero/4 mA and
Span/20 mA buttons simultaneously to exit the calibration mode. 
NOTE: If  the  buttons  are  not  pressed  for  approximately  4  minutes  in
calibrate  mode,  the  CRF2  will  automatically  revert  to  the  normal
operation mode. 
Restore Factory Calibration
The factory 4 and 20 mA calibration points may be restored by pressing
and holding both the Zero/4 mA and Span/20 mA buttons simultaneously
for 3 seconds. This must be done in the normal operation mode.
MAINTENANCE & REPAIR
Other  than  the  controls  mentioned  in  this  manual  there  are  no  user
maintenance adjustments or routine servicing required for this product.
The unit is not field repairable and should be returned to  the  factory  if
service is required. Disassembly or modifications made by the user will
void the warrantee and could impair the continued safety of the product.
If  repair  is  required  obtain  a  Returned  Goods Authorization  (RGA)
number and send the unit, freight prepaid, to the address below. Please
include a detailed description of the problem and conditions under which
the problem was encountered.
When  the  CLS2  with  Sanitary  Process  Connection  is  to  be  used  in  a
sanitary  or  hygenic  application,  the  unit  must  be  cleaned  and/or
sanitized in accordance with appropriate guidelines prior to installation.
The  CLS2  with  Sanitary  Process  Connection  is  suitable  for  “Clean  In
Place” methods.
Dwyer Instruments Inc.
Attn: Repair Department
102 Highway 212
Michigan City, IN 46360
P
OWER
S
UPPLY
R
ECEIVER/
R
EADOUT
––++
Z
ERO/
4
-MA
S
PAN/
2
0-MA
OUTPUT
Figure 3: Electrical Wiring Diagram




