How to Calibrate a 4–20 mA Vibration Transmitter with the AT-2040
The AT-2040 Portable Vibration Calibrator can be used to test and verify 4–20 mA vibration transmitters by applying a known vibration level and measuring the current-loop output from the transmitter.
Typical 4–20 mA checks
- Current output at known vibration level
- Transmitter scaling verification
- Loop wiring confirmation
- Full-scale range check
- Manual or automatic test workflow
- PDF and CSV report export
What the AT-2040 does during a 4–20 mA transmitter test
A 4–20 mA vibration transmitter converts vibration into a current-loop output. Instead of reading a raw accelerometer signal directly, the AT-2040 applies vibration to the sensor/transmitter assembly and measures the current output from the transmitter.
The AT-2040 includes a dedicated 4–20 mA input and can provide +24 V loop power for compatible transmitters. This allows the operator to verify whether the transmitter output matches the expected current for the applied vibration level.
AT-2040 4–20 mA support
Confirm the transmitter scaling and wiring
A 4–20 mA vibration transmitter must be tested against its configured full-scale range. Before testing, confirm the transmitter output units, full-scale value, wiring requirements, and whether the transmitter will use the AT-2040 loop supply or an external power source.
Check the full-scale range
Confirm what vibration level corresponds to 20 mA. For example, the transmitter may be configured for 0–1 in/s, 0–25 mm/s, 0–10 g, or another customer-specified range.
Confirm the expected output
For most linear transmitters, 4 mA represents zero output and 20 mA represents full scale. A mid-scale vibration level should produce a proportional current between 4 and 20 mA.
Verify loop wiring
Connect the transmitter according to its wiring diagram and confirm whether the AT-2040 +24 V supply or an external loop supply will be used.
Connect the 4–20 mA transmitter to the AT-2040
Mount the vibration transmitter or sensor assembly to the shaker reference platform using the correct mounting adapter. Then wire the transmitter output into the AT-2040 4–20 mA input terminals.
The AT-2040 4–20 mA input is designed for sensitivity testing of 4–20 mA transducers and vibration transmitters. The input also provides +24 V power for compatible loop-powered devices.
Connection checklist
- Transmitter mounted securely
- Correct adapter or fixture installed
- 4–20 mA output wired to the AT-2040 input
- Loop power confirmed
- 4–20 mA channel selected
- Full-scale range confirmed
Expected 4–20 mA output
A linear 4–20 mA transmitter normally maps vibration amplitude to current. The general relationship is:
Example
If a transmitter is scaled for 0–10 g and the AT-2040 applies 5 g, the expected output is approximately:
4 mA + 16 mA × (5 g ÷ 10 g)
= 4 mA + 8 mA
= 12 mAImportant
Always use the transmitter’s actual configured range. Some vibration transmitters may be scaled in velocity, acceleration, displacement, RMS, or peak units depending on the model and application.
Manual 4–20 mA transmitter test
Manual mode is useful when you want to check one vibration point, troubleshoot a transmitter, verify wiring, or confirm that the loop output changes correctly as the vibration level changes.
Open Vibration Output
From the main menu, select Vibration Output.
Select 4–20 mA
Tap the Channel button and select 4–20 mA.
Select units
Select the vibration units that match the transmitter configuration, such as velocity or acceleration.
Set frequency and amplitude
Use the knobs or touchscreen entry fields to set the test frequency and target vibration level.
Start the test
Select Start and allow the vibration level and transmitter output to stabilize.
Compare current output
Compare the measured mA output to the expected value based on the transmitter full-scale range.
What to watch during the test
During a 4–20 mA transmitter test, the operator should monitor both the mechanical vibration level and the transmitter’s current-loop response.
Live vibration
Shows the actual shaker vibration output in the selected units.
4–20 mA response
Confirms whether the transmitter current output matches the expected value.
Output level
Helps identify whether the shaker is approaching its output capability at the selected frequency and payload.
THD / displacement
Helps identify high distortion, excessive displacement, or conditions outside the best test range.
Run an automatic 4–20 mA transmitter test
For repeatable calibration or production verification, use the AT-2040 Sensor Test mode. The automatic test runs through stored test points, displays the results in graph or table view, and saves the data to onboard memory.
Automatic test records
The automatic test screen can show test status, reference reading, current step, deviation relative to the reference frequency, serial number, graph/table view, and Start/Stop control.
When the test is complete, the results are saved onboard and can be exported later from the Reports screen.
Typical 4–20 mA transmitter calibration setup
Exact test points should be based on the transmitter datasheet, configured full-scale range, customer requirements, and your laboratory procedure.
| Setup item | Typical choice | Why it matters |
|---|---|---|
| Sensor type | 4–20 mA vibration transmitter | Selects the correct current-loop input path. |
| Loop power | AT-2040 +24 V supply or external supply | The transmitter must be powered correctly for the loop output to operate. |
| Full-scale range | Customer or transmitter configured range | Used to calculate the expected current output. |
| Reference frequency | Often 100 Hz or customer-defined | Used as the main response verification point. |
| Amplitude | Known vibration level within the transmitter range | Determines the expected current output between 4 and 20 mA. |
| Output format | PDF certificate and CSV data | Supports customer records, quality systems, and further analysis. |
Common 4–20 mA check points
For a linear transmitter, current output should increase proportionally between 4 mA and 20 mA.
| Applied vibration | Percent of full scale | Expected output |
|---|---|---|
| 0% of full scale | 0% | 4.0 mA |
| 25% of full scale | 25% | 8.0 mA |
| 50% of full scale | 50% | 12.0 mA |
| 75% of full scale | 75% | 16.0 mA |
| 100% of full scale | 100% | 20.0 mA |
Export calibration results
After the 4–20 mA transmitter test is complete, the AT-2040 stores the result in onboard memory. Reports can be recalled and exported as PDF or CSV files for documentation, review, or customer delivery.
Report outputs
- PDF calibration certificate
- CSV measured data
- Sensor or transmitter serial number
- Frequency points
- Applied vibration levels
- Measured current-loop response
Pass/fail decisions are controlled by your lab procedure
The AT-2040 provides measured data and calibration records. It does not force a universal pass/fail decision because laboratories may use different tolerances, uncertainty budgets, and decision rules.
When issuing a statement of conformity, apply your own ISO 17025 decision rule or the decision rule requested by your customer.
Common 4–20 mA transmitter calibration problems
No current output
Confirm the 4–20 mA channel is selected, loop wiring is correct, and the transmitter is powered by the AT-2040 +24 V supply or by the required external supply.
Incorrect current value
Verify the transmitter full-scale range, RMS/Peak setting, vibration units, and whether the expected current calculation matches the transmitter configuration.
Amplitude limit warning
Reduce the vibration level, check the payload weight, or use a different frequency point. Shaker output limits depend on frequency and sensor mass.
Agate Technology can help you set up the right AT-2040 workflow.
Whether you are verifying one vibration transmitter at a time or building an automated calibration process, the AT-2040 can support manual testing, automatic sweeps, PDF certificates, and CSV export.
