Alliance Sensors S2A User manual

Quick Start Guide for S2A LVDT Signal Conditioner
1. Default Settings: The S2A's factory default LVDT excitation frequency is 3 kHz, which works for most LVDTs,
and the default DC output is 0 to 10 Volts. If you can utilize the default settings for excitation frequency and DC
output, skip to Step 3. Otherwise, open the S2A module’s case by pushing the locking tab inward on both of the thin
sides and sliding the case rearward to expose the two circuit-board-mounted DIP switches, DS1 and DS2.
2. Set the pcb-mounted DIP switches: LVDT excitation frequency can be changed by setting DS2-1 and DS2-2
according to the left side label or to Table 1 on S2A manual page 3. The DC output can be changed by setting DS1
on the pc board according to the left side label or to Table 2 on S2A manual page 3. When all DIP switch changes
are finished, slide the pc board back into the module’s case on its internal tracks and snap the two sections of the
case back together.
3. Mount the module: Remove the color-coded plugs from the S2A module and install the module on the DIN rail
by hooking the bottom of the module’s rear edge under the bottom edge of the rail, and then pressing the module
back against the rail until the spring-loaded rail catch engages the top edge of the rail. To remove the module from
the DIN rail, insert a flat-bladed screwdriver into the slot in the metal catch at the top rear of the module, lift the
catch upward, and disengage the module from the rail.
4. Make the I/O connections: Following the connections on the right side label or in Table 3 on S2A manual page
3, and the schematics on the reverse side of this sheet or in Figure 4 on S2A manual page 4, connect the color-
coded screw-terminal plugs at least to the LVDT's primary and secondaries (and the secondaries’ junction point if
needed), to DC power, and to the input of the PLC, control system, or analog output indicator. Connections to a
failure alarm or the master/slave bus can also be made at this time. When finished, insert the colored plugs
completely back into the corresponding colored jacks on the module.
5. Calibrate the LVDT’s core positions: Turn on the DC power and allow the module to warm up for at least 15
minutes before beginning the calibration procedure. The red POWER LED should glow steadily and the green
LEDs should be off, except the PLED will be steady on if the module is a master (manual page 6) or is operating
stand-alone. If any of the green LEDs are flashing, check the LVDT's connections: flashing Pindicates open
primary and flashing Sindicates open secondary. With power applied and the red POWER LED on, calibration can
proceed. Note: The LVDT’s core must not protrude from the LVDT at any point during the calibration process or
erroneous calibration will result.
►Shift the module into CALIBRATION mode by simultaneously depressing both the FULL SCALE and ZERO
buttons until the red POWER LED begins flashing. The module is now in CALIBRATION mode
► One of the green LEDs will be illuminated, indicating that the LVDT’s core is on one side or the other of null, or
at null. As the LVDT’s core is moved inward, that LED will go out and the middle LED will come on (showing the
LVDT is at null), then the middle LED will go out and the LED on the opposite end (compared to the first green LED
that was on) will come on. Adjust the LVDT core’s position until the middle green LED is on. The LVDT’s core is
now approximately at its null or mid-range position.
► Move the workpiece whose position is being measured so that it is located at the middle of its range of motion
when the LVDT’s core is at its null position. Mechanically couple the LVDT core to the workpiece in this position.
Now, move the workpiece to the desired Full Scale (end of travel) position and depress the FULL SCALE
pushbutton until the green (+) LED flashes once and the (-) LED lights up.
► Next, move the workpiece coupled to the LVDT’s core to the Zero (start of travel) position at the other end of its
range of motion and depress the ZERO pushbutton until the green (-) LED flashes once.
► If one (or both) of the green LEDs is still flashing, rerun the calibration procedure by moving the workpiece and
the coupled core to the end position indicated by the flashing LED and depressing its nearby button. The red LED
should be flashing, showing that the module is still in CALIBRATION mode. To return to RUN mode, depress both
the FULL SCALE and the ZERO buttons simultaneously for about 3 seconds until the green LEDs go out and the
red POWER LED turns on steady. Verify that the analog output and its directional sense (slope) is that which was
desired. If the output slope is reversed, switch DS2-3 to ON.
The complete S2A Instruction Manual may be downloaded from: www.alliancesensors.com
P/N 5700-0015, Rev C Aug. 1, 2019

a) 3-Wire LVDTs/RVDTs (see note 4)
b) 4-Wire LVDTs/RVDTs
c) 5-Wire LVDTs/RVDTs
d) 6-Wire LVDTs/RVDTs (see note 5)
e) Half-Bridges and GE LVRTs
(see note 4)
Notes:
1. J1-1 through J1-4 and J2-1 are connections to signal
conditioner’s screw terminal plugs.
2. LVDT/RVDT secondary windings are shown connected
in series-opposition, where ●indicates the windings’
magnetic polarization.
3. Letters in parentheses are connector pinouts for typical
5- and 6-wire LVDTs or RVDTs and for GE half-bridge-
style LVRTs.
4. Both a 3-wire LVDT/RVDT and a half-bridge (LVRT)
connection require moving J7 to the high output
position and moving J10 to the half-bridge position.
5. 6-wire LVDTs or RVDTs require the secondaries to be
connected externally in series-opposition, preferably
as close to the sensor as practical.
LVDT or RVDT and Half-Bridge (LVRT) Wiring Connections to S2A Signal Conditioner
P/N 5700-0015, Rev C Aug. 1, 2019