Measurement SG 1/4 bridge (quarter-bridge) 2/3-wire connection

Notes

By a user-side adjustment with a connected bridge sensor, the measurement uncertainity related to gain and offset error can be significant reduced.

The integrated switcheable shunt resistor can be used to generate a predictable detuning or, in case of deviation, a correction factor.

To calculate the quarter-bridge:

Measurement SG 1/4 bridge (quarter-bridge) 2/3-wire connection 1:
Connection of the quarter bridge

Explanation:

 

The strain relationship (µStrain, µε) is as follows:

Measurement SG 1/4 bridge (quarter-bridge) 2/3-wire connection 2:

For the quarter-bridge, N=1 always applies.

The relationship between UBridge/UExc and ∆R1 is non-linear:

Measurement SG 1/4 bridge (quarter-bridge) 2/3-wire connection 3:
Relationship between UBridge/UExc and ∆R1

The EPP3504/ ERP3504 devices apply internal linearization so that the output is already linearized

Measurement SG 1/4 bridge (quarter-bridge) 2/3-wire connection 4:

since the internal calculation is based on UExc'.

Measurement mode

StrainGauge/SG 1/4-bridge 120 Ω 2/3-wire

32 mV/V

8 mV/V

4 mV/V (comp.) 5)

2 mV/V (comp.) 5)

Measuring range, nominal

±32 mV/V [corresponds to ±64,000 µε at K=2]

120 ± 15.36 Ω

±8 mV/V [corresponds to ±16,000 µε at K=2]

120 ± 3.84 Ω

±4 mV/V [corresponds to ±8,000 µε at K=2]

120 ± 1.92 Ω

±2 mV/V [corresponds to ±4,000 µε at K=2]

120 ± 0.96 Ω

Measuring range, end value (FSV)

32 mV/V

8 mV/V

4 mV/V

2 mV/V

Measuring range, technically usable

±34.359... mV/V

±8.589... mV/V

±4.294... mV/V

±2.147... mV/V

PDO resolution

24 bit (including sign)

PDO LSB (Extended Range)

0.128 ppm
4.096 nV/V

0.128 ppm
1.024 nV/V

0.128 ppm
0.512 nV/V

0.128 ppm
0.256 nV/V

PDO LSB (Legacy Range)

0.119… ppm
3.814.. nV/V

0.119… ppm
0.9535 nV/V

0.119… ppm
0.47675 nV/V

0.119… ppm
0.238375 nV/V

Preliminary specifications:

Measurement mode

StrainGauge/SG 1/4-bridge 120 Ω 2/3-wire

32 mV/V

8 mV/V

4 mV/V (comp.) 5)

2 mV/V (comp.) 5)

Basic accuracy: Measuring deviation at 23°C, with averaging, typ. 2)

without Offset

< ±0.052%FSV
< ±520 ppmFSV
< ±16.6 µV/V

< ±0.16%FSV
< ±1600 ppmFSV
< ±12.8 µV/V

< ±0.32%FSV
< ±3200 ppmFSV
< ±12.8 µV/V

< ±0.64%FSV
< ±6400 ppmFSV
< ±12.8 µV/V

with Offset

< ±0.2%FSV
< ±2000 ppmFSV
< ±64 µV/V

< ±0.4%FSV
< ±4000 ppmFSV
< ±32.0 µV/V

< ±0.8%FSV
< ±8000 ppmFSV
< ±32.0 µV/V

< ±1.6%FSV
< ±16000 ppmFSV
< ±32.0 µV/V

Offset/Zero point deviation (at 23°C) 4)

EOffset

1920 ppmFSV

7840 ppmFSV

15680 ppmFSV

31360 ppmFSV

Gain/scale/amplification deviation (at 23°C)

EGain

320 ppm

880 ppm

1760 ppm

3520 ppm

Non-linearity over the whole measuring range

ELin

400 ppmFSV

1300 ppmFSV

2600 ppmFSV

5200 ppmFSV

Repeatability (at 23°C)

ERep

50 ppmFSV

200 ppmFSV

400 ppmFSV

800 ppmFSV

Common-mode rejection ratio (without filter) 3)

tbd.

tbd.

tbd.

tbd.

Common-mode rejection ratio (with 50 Hz FIR filter) 3)

tbd.

tbd.

tbd.

tbd.

Temperature coefficient, typ.

TcGain

40 ppm/K

96 ppm/K

192 ppm/K

384 ppm/K

TcOffset

100 ppmFSV/K
3.2 µV/V/K

360 ppmFSV/K
2.88 µV/V/K

720 ppmFSV/K
2.88 µV/V/K

1440 ppmFSV/K
2.88 µV/V/K

Largest short-term deviation during a specified electrical interference test

tbd. %FSV

 

tbd. %FSV

 

tbd. %FSV

 

tbd. %FSV

 

Input impedance ±Input 1

Differential

tbd.

tbd.

tbd.

tbd.

CommonMode

tbd.

tbd.

tbd.

tbd.

Input impedance ±Input 2

3-wire

 

Differential

tbd.

tbd.

tbd.

tbd.

CommonMode

tbd.

tbd.

tbd.

tbd.

Noise (with/ without filtering)/ preliminary data:

Measurement mode

StrainGauge/SG 1/4-bridge 120 Ω 2/3-wire

32 mV/V

8 mV/V

4 mV/V (comp.) 5)

2 mV/V (comp.) 5)

Noise (without filtering, at 23°C)

ENoise, PtP

285.0 ppmFSV
2227 digits
9.12 µV/V

< 1000.0 ppmFSV
< 7813 digits
< 8.0 µV/V

< 2000.0 ppmFSV
< 15625 digits
< 8.0 µV/V

< 4000.0 ppmFSV
< 31250 digits
< 8.0 µV/V

ENoise, RMS

50.0 ppmFSV
391 digits
1.6 µV/V

< 150.0 ppmFSV
< 1172 digits
< 1.2 µV/V

< 300.0 ppmFSV
< 2344 digits
< 1.2 µV/V

< 600.0 ppmFSV
< 4688 digits
< 1.2 µV/V

Max. SNR

86.0 dB

> 76.5 dB

> 70.5 dB

> 64.4 dB

Noisedensity@1kHz

0.02 Measurement SG 1/4 bridge (quarter-bridge) 2/3-wire connection 5:

< 0.02 Measurement SG 1/4 bridge (quarter-bridge) 2/3-wire connection 6:

< 0.02 Measurement SG 1/4 bridge (quarter-bridge) 2/3-wire connection 7:

< 0.02 Measurement SG 1/4 bridge (quarter-bridge) 2/3-wire connection 8:

Noise (with 50 Hz FIR filter, at 23°C)

ENoise, PtP

20.0 ppmFSV
156 digits
0.64 µV/V

< 60.0 ppmFSV
< 469 digits
< 0.48 µV/V

< 120.0 ppmFSV
< 938 digits
< 0.48 µV/V

< 240.0 ppmFSV
< 1875 digits
< 0.48 µV/V

ENoise, RMS

4.0 ppmFSV
31 digits
0.13 µV/V

< 12.0 ppmFSV
< 94 digits
< 0.1 µV/V

< 24.0 ppmFSV
< 188 digits
< 0.1 µV/V

< 48.0 ppmFSV
< 375 digits
< 0.1 µV/V

Max. SNR

108.0 dB

98.4 dB

> 92.4 dB

> 86.4 dB

Measurement mode

StrainGauge/SG 1/4-bridge 350 Ω 2/3-wire

32 mV/V

8 mV/V

4 mV/V (comp.) 5)

2 mV/V (comp.) 5)

Measuring range, nominal

±32 mV/V [corresponds to ±64,000 µε at K=2]

350 ± 44.8 Ω

±8 mV/V [corresponds to ±16,000 µε at K=2]

350 ± 11.2 Ω

±4 mV/V [corresponds to ±8,000 µε at K=2]

350 ± 5.6 Ω

±2 mV/V [corresponds to ±4,000 µε at K=2]

350 ± 2.8 Ω

Measuring range, end value (FSV)

32 mV/V

8 mV/V

4 mV/V

2 mV/V

Measuring range, technically usable

±34.359... mV/V

±8.589... mV/V

±4.294... mV/V

±2.147... mV/V

PDO resolution

24 bit (including sign)

PDO LSB (Extended Range)

0.128 ppm
4.096 nV/V

0.128 ppm
1.024 nV/V

0.128 ppm
0.512 nV/V

0.128 ppm
0.256 nV/V

PDO LSB (Legacy Range)

0.119… ppm
3.814.. nV/V

0.119… ppm
0.9535 nV/V

0.119… ppm
0.47675 nV/V

0.119… ppm
0.238375 nV/V

Preliminary specifications:

Measurement mode

StrainGauge/SG 1/4-bridge 350 Ω 2/3-wire

32 mV/V

8 mV/V

4 mV/V (comp.) 5)

2 mV/V (comp.) 5)

Basic accuracy: Measuring deviation at 23°C, with averaging, typ. 2)

without Offset

< ±0.044%FSV
< ±440 ppmFSV
< ±14 µV/V

< ±0.16%FSV
< ±1600 ppmFSV
< ±12.8 µV/V

< ±0.32%FSV
< ±3200 ppmFSV
< ±12.8 µV/V

< ±0.64%FSV
< ±6400 ppmFSV
< ±12.8 µV/V

with Offset

< ±0.2%FSV
< ±2000 ppmFSV
< ±64 µV/V

< ±0.4%FSV
< ±4000 ppmFSV
< ±32.0 µV/V

< ±0.8%FSV
< ±8000 ppmFSV
< ±32.0 µV/V

< ±1.6%FSV
< ±16000 ppmFSV
< ±32.0 µV/V

Offset/Zero point deviation (at 23°C) 4)

EOffset

1940 ppmFSV

7840 ppmFSV

15680 ppmFSV

31360 ppmFSV

Gain/scale/amplification deviation (at 23°C)

EGain

240 ppm

760 ppm

1520 ppm

3040 ppm

Non-linearity over the whole measuring range

ELin

360 ppmFSV

1500 ppmFSV

3000 ppmFSV

6000 ppmFSV

Repeatability (at 23°C)

ERep

50 ppmFSV

200 ppmFSV

400 ppmFSV

800 ppmFSV

Common-mode rejection ratio (without filter) 3)

tbd.

tbd.

tbd.

tbd.

Common-mode rejection ratio (with 50 Hz FIR filter) 3)

tbd.

tbd.

tbd.

tbd.

Temperature coefficient, typ.

TcGain

24 ppm/K

100 ppm/K

200 ppm/K

400 ppm/K

TcOffset

60 ppmFSV/K
1.92 µV/V/K

220 ppmFSV/K
1.76 µV/V/K

440 ppmFSV/K
1.76 µV/V/K

880 ppmFSV/K
1.76 µV/V/K

Largest short-term deviation during a specified electrical interference test

tbd. %FSV

 

tbd. %FSV

 

tbd. %FSV

 

tbd. %FSV

 

Input impedance ±Input 1

Differential

tbd.

tbd.

tbd.

tbd.

CommonMode

tbd.

tbd.

tbd.

tbd.

Input impedance ±Input 2

3-wire

 

 

 

 

Differential

tbd.

tbd.

tbd.

tbd.

CommonMode

tbd.

tbd.

tbd.

tbd.

Noise (with/ without filtering)/ preliminary data:

Measurement mode

StrainGauge/SG 1/4-bridge 350 Ω 2/3-wire

 

32 mV/V

8 mV/V

4 mV/V (comp.) 5)

2 mV/V (comp.) 5)

Noise (without filtering, at 23°C)

ENoise, PtP

290.0 ppmFSV
2266 digits
9.28 µV/V

< 1000.0 ppmFSV
< 7813 digits
< 8.0 µV/V

< 2000.0 ppmFSV
< 15625 digits
< 8.0 µV/V

< 4000.0 ppmFSV
< 31250 digits
< 8.0 µV/V

ENoise, RMS

50.0 ppmFSV
391 digits
1.6 µV/V

< 160.0 ppmFSV
< 1250 digits
< 1.28 µV/V

< 320.0 ppmFSV
< 2500 digits
< 1.28 µV/V

< 640.0 ppmFSV
< 5000 digits
< 1.28 µV/V

Max. SNR

86.0 dB

> 75.9 dB

> 69.9 dB

> 63.9 dB

Noisedensity@1kHz

0.02 Measurement SG 1/4 bridge (quarter-bridge) 2/3-wire connection 9:

< 0.02 Measurement SG 1/4 bridge (quarter-bridge) 2/3-wire connection 10:

< 0.02 Measurement SG 1/4 bridge (quarter-bridge) 2/3-wire connection 11:

< 0.02 Measurement SG 1/4 bridge (quarter-bridge) 2/3-wire connection 12:

Noise (with 50 Hz FIR filter, at 23°C)

ENoise, PtP

15.0 ppmFSV
117 digits
0.48 µV/V

< 50.0 ppmFSV
< 391 digits
< 0.4 µV/V

< 100.0 ppmFSV
< 781 digits
< 0.4 µV/V

< 200.0 ppmFSV
< 1563 digits
< 0.4 µV/V

ENoise, RMS

3.0 ppmFSV
23 digits
0.1 µV/V

< 9.0 ppmFSV
< 70 digits
< 0.07 µV/V

< 18.0 ppmFSV
< 141 digits
< 0.07 µV/V

< 36.0 ppmFSV
< 281 digits
< 0.07 µV/V

Max. SNR

110.5 dB

100.9 dB

> 94.9 dB

> 88.9 dB

Measurement mode

StrainGauge/SG 1/4-bridge 1 kΩ 2/3-wire

 

32 mV/V

8 mV/V

4 mV/V (comp.) 5)

2 mV/V (comp.) 5)

Measuring range, nominal

±32 mV/V [corresponds to ±64,000 µε at K=2]

1000 ± 128 Ω

±8 mV/V [corresponds to ±16,000 µε at K=2]

1000 ± 32 Ω

±4 mV/V [corresponds to ±8,000 µε at K=2]

1000 ± 16 Ω

±2 mV/V [corresponds to ±4,000 µε at K=2]

1000 ± 8 Ω

Measuring range, end value (FSV)

32 mV/V

128 Ω

8 mV/V

32 Ω

4 mV/V

16 Ω

2 mV/V

8 Ω

Measuring range, technically usable

±34.359... mV/V

±8.589... mV/V

±4.294... mV/V

±2.147... mV/V

PDO resolution

24 bit (including sign)

PDO LSB (Extended Range)

0.128 ppm
4.096 nV/V

0.128 ppm
1.024 nV/V

0.128 ppm
0.512 nV/V

0.128 ppm
0.256 nV/V

PDO LSB (Legacy Range)

0.119… ppm
3.814.. nV/V

0.119… ppm
0.9535 nV/V

0.119… ppm
0.47675 nV/V

0.119… ppm
0.238375 nV/V

Preliminary specifications:

Measurement mode

StrainGauge/SG 1/4-bridge 1 kΩ 2/3-wire

 

32 mV/V

8 mV/V

4 mV/V (comp.) 5)

2 mV/V (comp.) 5)

Basic accuracy: Measuring deviation at 23°C, with averaging, typ. 2)

without Offset

< ±0.04%FSV
< ±400 ppmFSV
< ±12.8 µV/V

< ±0.13%FSV
< ±1300 ppmFSV
< ±10.4 µV/V

< ±0.26%FSV
< ±2600 ppmFSV
< ±10.4 µV/V

< ±0.52%FSV
< ±5200 ppmFSV
< ±10.4 µV/V

with Offset

< ±0.2%FSV
< ±2000 ppmFSV
< ±64 µV/V

< ±0.4%FSV
< ±4000 ppmFSV
< ±32 µV/V

< ±0.8%FSV
< ±8000 ppmFSV
< ±32 µV/V

< ±1.6%FSV
< ±16000 ppmFSV
< ±32 µV/V

Offset/Zero point deviation (at 23°C) 4)

EOffset

1960 ppmFSV

7880 ppmFSV

15760 ppmFSV

31520 ppmFSV

Gain/scale/amplification deviation (at 23°C)

EGain

210 ppm

610 ppm

1220 ppm

2440 ppm

Non-linearity over the whole measuring range

ELin

330 ppmFSV

1120 ppmFSV

2240 ppmFSV

4480 ppmFSV

Repeatability (at 23°C)

ERep

50 ppmFSV

240 ppmFSV

480 ppmFSV

960 ppmFSV

Common-mode rejection ratio (without filter) 3)

tbd.

tbd.

tbd.

tbd.

Common-mode rejection ratio (with 50 Hz FIR filter) 3)

tbd.

tbd.

tbd.

tbd.

Temperature coefficient, typ.

TcGain

26 ppm/K

50 ppm/K

100 ppm/K

200 ppm/K

TcOffset

120 ppmFSV/K
3.84 µV/V/K

460 ppmFSV/K
3.68 µV/V/K

920 ppmFSV/K
3.68 µV/V/K

1840 ppmFSV/K
3.68 µV/V/K

Largest short-term deviation during a specified electrical interference test

tbd. %FSV

 

tbd. %FSV

 

tbd. %FSV

 

tbd. %FSV

 

Input impedance ±Input 1

Differential

tbd.

tbd.

tbd.

tbd.

CommonMode

tbd.

tbd.

tbd.

tbd.

Input impedance ±Input 2

3-wire

No usage of this input in this mode

Differential

tbd.

tbd.

tbd.

tbd.

CommonMode

tbd.

tbd.

tbd.

tbd.

Noise (with/ without filtering)/ preliminary data:

Measurement mode

StrainGauge/SG 1/4-bridge 1 kΩ 2/3-wire

 

32 mV/V

8 mV/V

4 mV/V (comp.) 5)

2 mV/V (comp.) 5)

Noise (without filtering, at 23°C)

ENoise, PtP

350.0 ppmFSV
2734 digits
11.2 µV/V

< 820.0 ppmFSV
< 6406 digits
< 6.56 µV/V

< 1640.0 ppmFSV
< 12813 digits
< 6.56 µV/V

< 3280.0 ppmFSV
< 25625 digits
< 6.56 µV/V

ENoise, RMS

70.0 ppmFSV
547 digits
2.24 µV/V

< 140.0 ppmFSV
< 1094 digits
< 1.12 µV/V

< 280.0 ppmFSV
< 2188 digits
< 1.12 µV/V

< 560.0 ppmFSV
< 4375 digits
< 1.12 µV/V

Max. SNR

83.1 dB

> 77.1 dB

> 71.1 dB

> 65.0 dB

Noisedensity@1kHz

0.03 Measurement SG 1/4 bridge (quarter-bridge) 2/3-wire connection 13:

< 0.02 Measurement SG 1/4 bridge (quarter-bridge) 2/3-wire connection 14:

< 0.02 Measurement SG 1/4 bridge (quarter-bridge) 2/3-wire connection 15:

< 0.02 Measurement SG 1/4 bridge (quarter-bridge) 2/3-wire connection 16:

Noise (with 50 Hz FIR filter, at 23°C)

ENoise, PtP

85.0 ppmFSV
664 digits
2.72 µV/V

< 48.0 ppmFSV
< 375 digits
< 0.38 µV/V

< 96.0 ppmFSV
< 750 digits
< 0.38 µV/V

< 192.0 ppmFSV
< 1500 digits
< 0.38 µV/V

ENoise, RMS

14.0 ppmFSV
109 digits
0.45 µV/V

< 8.0 ppmFSV
< 63 digits
< 0.06 µV/V

< 16.0 ppmFSV
< 125 digits
< 0.06 µV/V

< 32.0 ppmFSV
< 250 digits
< 0.06 µV/V

Max. SNR

97.1 dB

101.9 dB

> 95.9 dB

> 89.9 dB

2) In real bridge measurement, an offset adjustment is usually carried out after installation. The given offset specification of the box module is therefore practically irrelevant. Therefore, specification values with and without offset are given here. In practice, the offset component can be eliminated by the functions Features and also Features of the box module or in the controller by a higher-level tare function. The offset deviation of a bridge measurement over time can change, therefore Beckhoff recommends a regular offset adjustment or careful observation of the change.

3) Values related to a common mode interference between SGND and internal ground.

4) The offset specification does not apply to 2-wire operation, since the offset is increased on the device side. Therefore, a system-side offset adjustment is recommended, see Tare- or ZeroOffset function. The final targeting basic acuuracy within the 2-wire operation is mainingly dependent by the quality of this system-side offset adjustment.

5) The channel measures electrically to 8 mV/V, but displays its measured value scaled to 2 or 4 mV/V. The Compensated function facilitates measurement of low levels even with high offset.

Notice

Transition resistances of the connection contacts

The transition resistance values of the connection contacts affect the measurement. The measuring accuracy can be further increased by a user-side adjustment with the signal connection plugged in.

The temperature sensitivity of the box module and thus of the measurement setup can be reduced if an external, more temperature-stable supplementary resistor is used for operation of the box module in half-bridge or even full-bridge mode instead of the internal supplementary resistor for quarter-bridge mode.