background image

Note:

  Also on the edge of the PC board are two adjustment 

potentiometers, R7 and R8, and a 3-pin terminal TB1.  

Pot R7 is for tweaking the 4 mA output level.  Pot R8 is 

for tweaking the 20 mA output level.  These two pots are 

factory-adjusted, and the user normally should not have to 

adjust them.  It is best to leave these two pots alone. 

 

  The user normally should not have to disconnect the 

 

  3-wire cable from the SG1000F. But if they do so, they 

must reconnect the 3-wire cable to the SG1000F as 

follows: 

 

  •  Power supply (+24Vdc) terminal red wire to TB1-1.

 

  •  4-20mA signal clear wire to TB1-2.

 

  •  Power supply (-) terminal black wire to TB1-3.

2)   Before entering Calibration Mode, set the direction 

switch SW1 on the SG1000F’s PC board to the proper 

position for the application.

SW1 tells the SG1000F the direction the encoder turns, 

CW or CCW, as the process is moved from the fully-closed 

to the fully-open position.  The CW or CCW direction is 

defined via the viewer looking at the back-cover-end of the 

enclosure, and not the encoder-shaft-end of the enclosure:

•  If the encoder shaft turns in the CW direction as the 

process shaft is moved from the fully-closed to the fully-

open position, then set SW1 to the OFF position (i.e., 

toward the center of the PC board).  See Figure 4.

•  If the encoder shaft turns in the CCW direction as the 

process shaft is moved from the fully-closed to the fully-

open position, then set SW1 to the ON position (i.e., 

toward the edge of the PC board).  See Figure 4.

Note:

 The direction switch SW1 is monitored only briefly as 

the SG1000 enters into Calibration Mode. But once 

inside Calibration Mode, SW1 is no longer relevant.  

Hence, changing SW1 at this point has no effect.  

Because of this, SW1 must be set to the desired 

position before Calibration Mode is entered in order 

to capture the desired setting of SW1.

3)  There are two ways to enter Calibration Mode:  

•  One, remove the +24Vdc power, press-in and hold the 

calibration switch SW2, then reapply the +24Vdc power. 

(This is referred to as “power-up” entry into calibration 

mode).

•  Or two, while the SG1000 remains powered, press-in 

and hold the calibration switch SW2, for a constant 5 to 

6 seconds. (This is referred to as “on-the-fly” entry into 

calibration mode). 

  (Do not press SW2 multiple times or allow it to change state, 

just keep it pressed-in).  Continue to keep SW2 pressed-in 

for a few seconds until the SG1000 outputs a constant 12 mA 

from its signal line, then release the button.  

The SG1000F is now in the calibration mode

.

4)  Move the process shaft to the fully-closed position (i.e., 

0% open).

5)  Press the calibration switch SW2.

•  This captures the present encoder count.  This value is 

then used for the fully-closed position (0% open).

•  The output signal remains at 12 mA.

6)  Move the process shaft to the fully-open position (i.e., 

100% open).

Note

:  As the process shaft moves from fully-closed to fully-

open, the SG1000F’s encoder shaft must turn at least 

30º, but not more than a 718º turn (i.e. just shy of two 

full turns.)  Hence, if the shaft turns more than 718º, 

or less than 30º, then the SG1000F will 

not

 work 

properly for the application.

7)  Press the calibration switch SW2.

•  This captures the present encoder count.  This value is 

then used for the fully-open position (100% open).

• 

The SG1000F then automatically exits the calibration 

mode and enters the normal operating mode. 

Note:

 The calibration mode is exited at this point for both 

valid and invalid calibrations.  

For a valid calibration:  If the user does not 

immediately move the process shaft, then the 

output signal is 20 mA.  (Because the process shaft 

was left in the fully-open position from step 6, the 

output signal is at 100%, which is 20 mA). 

For an invalid calibration:  The output signal 

remains at 12 mA.

See the “

Valid Calibration” 

and

 “Invalid Calibration” 

sections

 

below for details regarding whether, or not, your 

SG1000F accepted the shaft’s two calibration positions.

8)  Replace the back-end-cover onto the SG1000F.

This ends the calibration procedure.

Valid Calibration (Normal Operating Behavior)

Assuming the user followed the calibration procedure 

correctly

the SG1000F behaves as follows:

•  When the process shaft is at the fully-closed position (0% 

open), the output signal is 4 mA.

•  When the process shaft is at the fully-open position (100% 

open), the output signal is 20 mA.

•  Any process shaft position between 0% open and 100% 

open is represented by the output signal being proportionally 

between 4 mA and 20 mA.

•  If the process shaft is moved to a position that is slightly 

beyond (outside of) the fully-closed (0% open) calibrated 

position, then the output signal remains at 4 mA.  This is 

known as 0% ‘run-out’, and it holds to a certain point.  If 

the encoder is turned far enough beyond the fully-closed 

calibrated position, then the encoder “wraps-around” and the 

output signal jumps to the fully-open value of 20 mA.

2-4

Free Catalog and Application Assistance

1.800.328.6170

Website: www.electro-sensors.com

990-002450 Revision C

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