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Omron Load Cell Module NX-RS1201

To get started with omron load cell module NX-RS1201 with Sysmac Studio. This modules supports 4 wire and 6 wire load cells. Load cell module are simple complex systems with ADC and amplifier. Amplifier amplifies and input signal from the load cell and ADC converts the amplified signal to digital value which can be used for the logic.

Required components​

  • NX/NJ Motion Controller
  • Load cell Module NX-RS1201

Add Module​

To add module to the CPU Rack or Remote IO Rack, Go to Configuration and Set in Multiview Explorer. Expand CPU/Expansion Racks and Select CPU Rack.

Select Load Cell Input Device in Toolbox Group and Select & Insert NX-RS1201 Ver1.0.

Wiring​

NX-RS1201 supports both 4 or 6 wire configuration.

4 Wire Connections​

   |   |         SHEALD         A1          B1
+--+---+----+   +------+      +-------------+
|    (OUT+) |<--|------|----->| SIG+ |  S+  |<----+
|           |   |      |      |------|------|     |
|    (OUT-) |<--|------|----->| SIG- |  S-  |<-+  |
|           |   |      |      |------|------|  |  |
|    (IN+)  |<--|------|----->| EXC+ | EXC+ |<-|--+
|           |   |      |      |------|------+  |
|    (IN-)  |<--|------|----->| EXC- | EXC- |<-+
|           |   +---+--+      |------|------|
|           |       |         |  NC  |  NC  |
+-----------+       |         |------|------|
  LOADCELL          |         |  NC  |  NC  |
  6-WIRE            |         |------|------|
                    +---------| SHLD | SHLD |
                              |------|------|
                        +-----|  SG  |  SG  |
                        |     +-------------+
                        |     A8          B8
                      EARTH

In 4 wire config, Signal wires are not provided by the load cell, To avoid module in to thinking, it's not connected to the load cell, S+, S- wires should be connected to EXC+ and EXC- respectively.

S+  --------------   EXC+
S-  --------------   EXC-

6 Wire Connections​

                      (SIG-)
   +----------------------------------------------+
   |                 (SIG+)                       |
   |   +----------------------------------------+ |
   |   |         SHEALD         A1          B1  | |
+--+---+----+   +------+      +-------------+   | |
|    (OUT+) |<--|------|----->| SIG+ |  S+  |<--+ |
|           |   |      |      |------|------|     |
|    (OUT-) |<--|------|----->| SIG- |  S-  |<----+
|           |   |      |      |------|------|
|    (IN+)  |<--|------|----->| EXC+ | EXC+ |
|           |   |      |      |------|------+
|    (IN-)  |<--|------|----->| EXC- | EXC- |
|           |   +---+--+      |------|------|
|           |       |         |  NC  |  NC  |
+-----------+       |         |------|------|
  LOADCELL          |         |  NC  |  NC  |
  6-WIRE            |         |------|------|
                    +---------| SHLD | SHLD |
                              |------|------|
                        +-----|  SG  |  SG  |
                        |     +-------------+
                        |     A8          B8
                      EARTH

Module Configuration​

To edit the configuration of the module, Right click on the module and select Edit unit Operation Settings.

Required parameters are as bellow

Load cell Rated Capacity​

Rated capacity can be obtained from the datasheet of the load cell and can as to setting. Standard operating rule of thumb is milligrams multiplier.

Let's assume Rated capacity is 5 KG. It is 5000 g and 5000000 mg. This can be set as Rated Capacity to measure the weight to smallest denominator milligram if the load cell is rated for it.

Standard Weight​

Standard weight is something we use for SPAN calibration of the load cell. Let's say given applicated, minimum measuring weight is 10g. Span can be calibrated at 10g for optimum results.

Rated capacity is set at 5000000 which is 5 KG. So, per gram value would be 1000 and for 10g value would be 10000.

Load cell Rated Output​

Load cell module amplifies the received voltage based on the given rated output the connected load cell.

This value can be found on the datasheet of the load cell. IT would be around 2mV/V on average. If it's not printed on load cell or not found on the datasheet, contact vendor/dealer/manufacturer.

Calibration​

Calibration is divided in to 2 parts.

To perform calibration, right click on the module and select Calibration and Data Trace. Remove all the obstruction and turn of any fans to avoid false calibration data. Wait for the Stable Status to turn from OFF to ON.

Zero Calibration​

Zero Calibration will set the current output of the load cell to the zero. It should be done with all the deadload including mounting hardware.

To perform Zero Calibration, Select Execute Zero Calibration in Calibration in Calibration and Data Trace.

Span Calibration​

SPan Calibration will calculate the output value and sets ADC values based on current wait and Standard Weight in the Operation Setting. It should be done after performing Zero Calibration and with standard weight as the load.

To perform Zero Calibration, Select Execute Span Calibration in Calibration in Calibration and Data Trace.

After executing the span calibration value from the load cell should be same as standard weight value.

Sample program​

Below is simple Structured Text/ST(IEC-61131) to measure the weight.

Loadcell_Value := N2_Ch1_Gross_Weight_Value_Force_Measurement_Value_DINT;
Loadcell_Capacity := REAL#5000;
Loadcell_Rated_Capacity := REAL#5000000;
One_Gram_Value := Loadcell_Rated_Cap / Loadcell_Capacity;
Loadcell_Weight :=(DINT_TO_REAL(Loadcell_Value)) / One_Gram_Value ;