The Role of Frequency Output in Flowmeters
Frequency output is one of the commonly used signal output methods for industrial flowmeters. It can convert instantaneous flow into pulse or frequency signals for acquisition by PLCs, DCSs, or counters. Compared with 4-20mA analog output, frequency output has stronger anti-interference capability and is suitable for long-distance transmission and high-precision totalizing.
This article uses Endress+Hauser's Promag 53 electromagnetic flowmeter, Promass 83 Coriolis mass flowmeter, and Prosonic 93 ultrasonic flowmeter as examples to explain the frequency output setup procedure.
Preparation Before Setup
Hardware and Wiring Confirmation
- Confirm that the transmitter is properly powered and the display can light up normally.
- Confirm that the frequency output terminals (usually terminals 24/25 or 26/27) are connected to the receiving device according to the wiring diagram.
- Check whether the cable shield is grounded at one end only to avoid pulse signal interference.
Parameter Preparation
- Clarify the required full-scale frequency (e.g., 0-10 kHz).
- Clarify the corresponding flow full-scale value and engineering unit.
- Confirm that the output mode is frequency output rather than pulse output.
Promag 53 Frequency Output Setup Steps
Enter the Output Configuration Menu
- Press the E key to enter the main menu, and use the +/- keys to select "Outputs".
- Select "Current output 2" or "Frequency output", and press E to confirm.
- Set the output type to Frequency.
Set Frequency Parameters
- Set End value frequency (full-scale frequency); the commonly used range is 0-10000 Hz.
- Set End value flow (the corresponding full-scale flow value) and its unit.
- Set Output signal to "Passive" or "Active" to match the receiving end.
- After saving, return to the measurement screen and observe whether the frequency output changes with flow.
Key Setup Points for Promass 83 and Prosonic 93
Promass 83
- Select the frequency output channel under "Setup" -> "Outputs".
- Mass flow or volume flow can be configured separately as the frequency output variable.
- Supports frequency range 0-10 kHz, which must match the PLC input card.
Prosonic 93
- Frequency output is often used for totalized flow pulse output.
- It is necessary to set the pulse value (flow corresponding to each pulse) and pulse width.
- Note that ultrasonic flowmeters are sensitive to bubbles and suspended solids. If the output fluctuates, first check the medium condition.
Parameter Comparison and Common Issues
| Item | Promag 53 | Promass 83 | Prosonic 93 |
|---|---|---|---|
| Output type | Frequency/Pulse | Frequency/Pulse | Frequency/Pulse |
| Full-scale frequency | 0-10 kHz | 0-10 kHz | 0-10 kHz |
| Output variable | Volume flow | Mass/Volume flow | Volume flow |
| Typical application | Water/Wastewater metering | Trade settlement | Open channel/Pipeline |
Common Troubleshooting
- No frequency output: Check whether the output is set to "Off" or whether the terminal wiring is loose.
- Frequency does not change with flow: Confirm whether the full-scale flow value is set correctly.
- Signal fluctuation: Check shield grounding and cable routing, and keep away from variable-frequency drive interference sources.
Summary
The core of frequency output setup is to match the full-scale flow with the full-scale frequency and ensure that the output type, wiring, and receiving device are consistent. By configuring in sequence according to the above steps, the frequency output commissioning of Promag 53, Promass 83, and Prosonic 93 can be completed quickly.