Electro-Sensors SG1000E User Manual

SG1000E Sub-Turn Shaft Monitor

SG1000E general description

The SG1000E is a Sub-Turn Shaft Monitor with a 4-20 mA
output. The SG1000E is a rugged, medium cost encoder-based
monitoring device that enables the end-user to very accurately
monitor a process shaft’s position, allowing very accurate
operations. The SG1000E has two modes: calibration mode,
and normal operating mode. A simple calibration procedure
teaches (programs) the SG1000E the fully-closed (0% open) and
fully-open (100% open) process positions. Once programmed,
the SG1000E outputs a 4 mA DC signal when the process is in
the fully-closed position, and outputs a 20 mA DC signal when
the process is in the fully-open position. Any process position
between fully-closed and fully-open, is represented by the output
signal being proportionally between 4 and 20 mA.

Physical Appearance and Installation Overview

Figure 1 is the front-view of the SG1000E, showing the encoder­output-shaft.

Cable

The SG1000E attaches to the process’s shaft, or similar rotating
mechanical component, using an “end-of-shaft” mounting
method. See Figure 2. The SG1000E’s encoder-shaft-end
screws into a single 3/8-inch diameter hole, to a depth of 0.625
inch, having 3/8” – 16 UNC-2B threads.
Even though the SG1000E is mounted to the process shaft via

the “end-of-shaft” mounting method, installation of exible

conduit and of the optional stabilizer bracket is recommended,

which allows the SG1000E to “oat” along with any wobble

of the process’s shaft while still preventing the SG1000E from
rotating along with that shaft (see Fig. 2).
Note: The stabilizer bracket’s U-bolt is slightly oversized
to provide about 1/8” of slack between it and the
SG1000E. The U-bolt’s slack prevents it from
rigidly clamping to the SG1000E’s conduit port.

Encoder-Shaft
3/8"-16 UNC-2A threads

Figure 1:

Electrical connections

The SG1000E’s electrical cable has three wires, plus a shield­wire. Connect as follows: (See Figure 3):

SG1000

Ammeter

(optional)

-

Clear 4-20mA

+

4-20mA

PLC , Etc.

250 to 500

ohm load

Requires

User Installed

Class 2 Isolated

+24Vdc

Power Supply

(+)

(-)

Red

Shield

Black

Figure 3:

• Connect the shield wire to the earth ground.

• Connect the black wire to the power-supply (-) terminal.

• Connect the red wire to the power-supply (+24 Vdc)
terminal.

• Connect the clear wire to a resistive load of 250 Ω to
500 Ω, (usually this load is internal to a PLC, etc.).

Note: The clear wire is the 4-20 mA DC output line.

The other side of the 250 Ω to 500 Ω load must be

connected to the power-supply (-) terminal.

• See Figure 4 below for related information.

Calibration Procedure

Calibration consists of teaching the SG1000E the encoder
values for the fully-closed (0% open) and fully-open (100%
open) positions. The eight calibration steps are as follows (once
the user is familiar with the calibration procedure they need only
follow the underlined portions as a quick calibration guide):

1) Remove (twist CCW) the back-end-cover from the
SG1000E.

This provides access to the edge of the SG1000E’s printed
circuit board, namely the direction switch SW1 (the slide
switch), and the calibration switch SW2 (the push-button
switch). See Figure 4 for locations of these switches.

CCW CW

SG1000

Process Shaft

Stabilizer bracket

U-Bolt

with slack

Flexible
conduit

(use is optional)

Figure 2:

6111 Blue Circle Drive
Minnetonka, MN 55343
Phone: [phone]
Fax: [phone]

ISO 9001:2000 Certied

Structural Framework

SW2

R8

R7

Ground

Screw

TB1

Red

Clear

Black

Shield

CW(OFF) CCW(ON)

SW1 Detail

SW1

Figure 4:

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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 SG1000E. But if they do so, they

must reconnect the 3-wire cable to the SG1000E 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 SG1000E’s PC board to the proper
position for the application.

SW1 tells the SG1000E 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

dened 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 fully­open 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 fully­open 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 briey 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-y” 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 SG1000E is now in the calibration mode.

4) Move the process shaft to the fully-closed position (i.e.,
0% open).

5) Momentarily 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 SG1000E’s encoder shaft must turn at least

5.6º, but not more than a 130º turn. Hence, if the
shaft turns more than 130º, or less than 5.6º, then the
SG1000E will not work properly for the application.

7) Momentarily press the calibration switch SW2.

• This captures the present encoder count. This value is
then used for the fully-open position (100% open).

• The SG1000E 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
SG1000E accepted the process shaft’s two calibration
positions.

8) Replace the back-end-cover onto the SG1000E.

This ends the calibration procedure.

Valid Calibration (Normal Operating Behavior)

Assuming the user followed the calibration procedure correctly,
the SG1000E 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

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990-002440 Revision D