SITRANS F M MAG 5000 Flowmeter: Resolving the ###### Display and Erroneous Totalizer Count

The Siemens SITRANS F M MAG 5000 is a 4-wire electromagnetic flow transmitter paired with MAG 1100, MAG 3100, and MAG 5100 W sensors in water, wastewater, chemical, food/beverage, and process industries. One of the most frequently reported field issues is the appearance of ###### on the front display paired with a totalizer that continues to count even when the line is genuinely idle. This reference explains why both symptoms occur, how to reset each totalizer independently, and the electrical and parameter checks required to stop the phantom count. The procedures apply to firmware revisions 2.00 through 4.05 of the MAG 5000/MAG 6000 HART transmitter family.

1. Problem Statement and Field Symptoms

The reported symptom set is consistent across multiple installations:

• Front display shows ###### instead of a numeric flow rate or totalizer value.
• Totalizer continues to advance even with upstream and downstream block valves closed (no flow).
• Performing a totalizer reset clears the count temporarily, but ###### returns within seconds and the count resumes.
• Low flow cut-off is left at the factory default of 1.5% of Qmax.
• No fault code (F-NN) appears in the status window, only the overflow hash.

The two symptoms are independent failure indicators: ###### is a display-range overflow of an 8-digit totalizer register, while the drifting totalizer indicates that the flow signal channel is non-zero when it should be zero. Treat both as separate root causes; fixing the totalizer does not necessarily clear the hash display, and clearing the hash display does not stop a noisy flow channel.

2. SITRANS F M MAG 5000 Display Architecture

The MAG 5000 transmitter uses a 3-row, 16-character alphanumeric display. Each row has its own meaning and behaves differently when the value overflows. The four windows are accessed in sequence using the up arrow key.

The 8-digit totalizer overflow is the most common cause of ###### in field reports. Each totalizer has 99,999,999 counts available, with automatic decimal placement based on configured engineering units. If the application flow is, for example, 50 m³/h, the totalizer fills in 8,333 hours, or roughly 347 days. In leak detection, batching, or any application without periodic reset, the register will eventually saturate. After saturation, the totalizer stops incrementing until reset, but the display remains pinned at ###### to indicate the register has been clipped.

3. Root Cause Analysis

Three independent causes can produce the reported symptom set. Diagnose all three before returning the meter to service. A reset that only addresses the display symptom will not fix the phantom-count issue, and a noise fix that does not reset a saturated register will not clear the hash display.

3.1 Saturated Totalizer Register

The totalizer has accumulated more than 8 digits and is parked at ######. This is a normal end-of-life event for an unreleased totalizer. The flow channel may be operating correctly; the issue is purely cosmetic until reset. A reset returns the register to 0.0 and resumes counting.

3.2 Phantom Flow Signal (No-Flow Drift)

With the line blocked, the flow channel should output exactly zero. If the totalizer continues to integrate, the sensor is delivering non-zero counts from one of the following causes:

• Electrode noise from poor grounding. MAG 5000 sensors must be installed with equipotential bonding. Without it, the electrodes pick up 50/60 Hz mains hum or VFD common-mode noise, integrated as low-level flow.
• Partially filled pipe. If air pockets or voids exist upstream or downstream of the sensor, the electrodes intermittently see liquid and read the air-liquid interface as flow.
• Air entrainment. Bubbles crossing the electrodes register as flow peaks. Typical sources: pump cavitation, vertical pipe runs with insufficient backpressure, recently drained and refilled lines.
• Contaminated electrodes. Oil, grease, scale, or magnetite buildup creates a DC offset on the electrode pair, interpreted as flow even with stationary liquid.
• Coil driver fault. If the magnetizing current is unstable or the coil driver output is asymmetric, the excitation waveform generates spurious electrode readings.
• Cross-talk or ground loop from parallel signal cables. Long cable runs in shared conduit with power cables inject common-mode noise.

3.3 Misconfigured Suppression

If the low flow cut-off is set to 0% and empty pipe detection is OFF, the transmitter does not suppress small signals. Even sub-m/s drift from electrical noise registers as flow and is integrated into the totalizer. The default 1.5% of Qmax is designed to suppress thermal noise and minor pickup, but a marginal installation with significant EMI may require 3-5% cut-off to fully suppress drift.

4. Prerequisites and Tools

5. Totalizer Reset Procedure (Menu 3)

The MAG 5000 has two independent totalizers (A and B). Field reports that reset did not clear the issue almost always refer to one of the totalizers being reset while the other continues to overflow. Both must be cleared to clear all ###### indications on the totalizer windows.

5.1 Local Keypad Reset

1. Press ENTER to enter the main menu. The display shows the first menu number.
2. Use ▲ / ▼ to navigate to menu 3 (Totalizers) and press ENTER.
3. Select 3.1 (Totalizer A) or 3.2 (Totalizer B) and press ENTER.
4. Choose RESET (clears to zero) and press ENTER.
5. Enter the operator password (factory default 1000) using the arrow keys and press ENTER.
6. Confirm YES at the prompt. The totalizer returns to 0.00 in the configured unit.
7. Repeat steps 3-6 for the second totalizer. Verify both displays show numeric values after reset.

5.2 HART Reset via Universal and Common Practice Commands

From a HART master, read totalizers with the following universal and common-practice commands:

Command 0:  Read unique identifier (manufacturer 0x005A, device type 0x0013)
Command 3:  Read PV (flow) and loop current
Command 13: Read dynamic variables (returns PV, SV, TV, FV with units)
Command 14: Read PV with current and percent of range
Command 48: Read additional device status (bit flags indicate totalizer A/B overflow)
Command 55: Read additional device variables (slot-based diagnostics)

To reset via HART, use SIMATIC PDM (recommended):

1. Open PDM and connect to the device. Use the device tag or poll address (default 0 for point-to-point).
2. Navigate to Device → Reset Totalizer A or Reset Totalizer B from the device menu.
3. Confirm. PDM prompts for write protection; enter password 1000 if required.
4. After reset, read command 48 and confirm the overflow bit is cleared for both totalizers.

5.3 Preset Value vs Reset vs Hold

The MAG 5000 supports three operations on each totalizer. Choose the operation that matches the field requirement.

6. Grounding and Electrical Noise Diagnostics

Phantom flow is almost always an electrical issue, not a meter issue. The Faraday law that governs the MAG 5000 measures induced voltage on the electrodes. Any voltage that is not proportional to flow registers as flow. The dominant noise sources are ground loops and 50/60 Hz mains pickup. The MAG 5000 uses bipolar pulse excitation at approximately 12.5 Hz (with 50 Hz mains) or 15 Hz (with 60 Hz mains) specifically to reject line-frequency noise, but this rejection is finite and breaks down with severe noise.

6.1 Grounding Topology Requirements

The sensor and adjacent piping must share a common ground potential. The minimum wiring is:

• Equipotential bonding strap between sensor flanges and adjacent pipe flanges. Use a 16 mm² (6 AWG) copper braid or stranded cable, as short as practical.
• Grounding rings (for lined pipes with non-conductive fluid) or grounding electrodes between the sensor and pipe.
• Functional Earth (FE) terminal on the transmitter connected to the same ground as the adjacent piping.
• Cable shield terminated at the transmitter end only; do not bond both ends (this creates a ground loop through the shield).
• PE/ground conductor in the supply cable sized per local electrical code (typically 1.5 mm² / 16 AWG minimum).

6.2 Measurement Procedure

1. Isolate the meter from the process (close block valves upstream and downstream; depressurize if necessary for electrode impedance testing).
2. With the line full of stationary liquid, measure the AC voltage between each electrode and the equipotential ground strap with a true-RMS multimeter. Acceptable noise level is below 5 mV RMS at 50/60 Hz. Readings above 20 mV indicate severe grounding or shielding issues.
3. Measure the resistance between each electrode and the equipotential ground strap with a megohmmeter at 500 V DC. Acceptable value: greater than 100 MΩ. Values below 1 MΩ indicate water ingress into the sensor housing or electrode coating.
4. Measure the resistance between the two electrodes. Expect 5-50 kΩ for clean water at typical conductivity (200-1000 µS/cm). Values outside this range indicate contamination, scaling, or open-circuit failure.
5. Measure the DC resistance of the magnet coil between terminals 81 and 82. Expect 40-120 Ω depending on sensor size; refer to the sensor nameplate. Open or shorted coil requires sensor replacement.

6.3 Cable Routing

Route the electrode and coil cables in a dedicated conduit, separated from power cables by a minimum of 200 mm (8 in) or by a grounded metal partition. Never run the sensor cable in the same tray as VFD output cables. If the installation is in a VFD-rich environment, use a double-shielded cable such as Siemens 6XV1830 series or equivalent. Maximum cable length between sensor and transmitter: 100 m for standard cable, up to 1000 m with special low-capacitance cable. Voltage drop on the coil circuit becomes the limit at long distances.

6.4 Common EMI Sources in Industrial Environments

7. Parameter Configuration: Low Flow Cut-Off and Empty Pipe

Two suppression parameters stop small signals from reaching the totalizer. The first is a software threshold; the second is an automatic physical sensor check.

For a process with known low-end noise of 1-2% of Qmax, set the low flow cut-off to 3-5% of Qmax to ensure margin. For batch applications where small quantities matter, leave at 1.5% but address the noise source at its origin (grounding, cable routing, EMI suppression). Setting cut-off too high suppresses legitimate low flow and reduces measurement accuracy below the threshold.

8. Empty Pipe Detection and Sensor Health Verification

Empty pipe detection (EPD) relies on a third electrode (or a measurement between the existing electrodes at a special frequency). When the pipe is full, the electrode is in contact with conductive liquid and the impedance to ground is low. When empty, the impedance is high. The transmitter reads this impedance and forces flow to zero when the threshold is crossed.

8.1 Enabling and Tuning EPD

1. Navigate to menu 1.6 and set to ON.
2. With the pipe confirmed full (no air pockets, no voids), navigate to 5.4 (EPD calibration) and select CALIBRATE. The transmitter learns the full-pipe impedance and stores it in non-volatile memory.
3. Confirm by draining the test section (or simulating empty pipe with a known test jig). The flow display should drop to zero within 30 s and the status window should show W-25.
4. Refill the pipe; flow display should resume within 30 s of refilling.

If EPD cannot be calibrated, the third electrode is contaminated, the EPD cable is damaged, or the process fluid conductivity is below 5 µS/cm. For high-purity water, condensate, or non-conductive fluids (oils, hydrocarbons without water content), EPD will not function reliably and should remain OFF. In these services, an external level switch or different flow technology (Coriolis, vortex) is preferable.

8.2 Sensor Coil and Electrode Health Diagnostics

Using HART command 55, read the following diagnostic variables. These are not visible on the front display and require PDM or a HART master.

9. Current Loop, Pulse Output, and HART Verification

After clearing the totalizer and addressing the noise source, verify the outputs reflect the corrected flow channel. A 4-20 mA loop that reads 4.00 mA at zero flow is the strongest indication that the noise source has been addressed.

9.1 4-20 mA Loop Check

1. Open the current loop at the receiver (or insert a multimeter in series at the transmitter terminals).
2. Force zero flow (close block valves).
3. Read current. Expect 4.00 mA ±0.02 mA. If higher than 4.02 mA, the channel is still drifting.
4. Apply a known flow (use a calibrated reference meter or full-scale Qmax from a test pump). Verify the current matches PV = (Flow/Qmax) × 16 + 4 mA within ±0.1% of span.
5. For HART, verify the loop has at least 250 Ω total resistance (250 Ω is the minimum for reliable HART communication).

9.2 Pulse Output Check

The pulse output (terminal 41/42) is configured in menu 2.3. Verify the pulse units match the totalizer units. If they are out of sync, the totalizer is integrating correctly but the pulse is on a different scale, leading to counting errors at the receiver PLC or flow computer. Pulse weight is configured as volume per pulse (e.g., 1 m³ per pulse, 10 L per pulse). Maximum pulse frequency is 5 kHz on the standard output; exceeding this causes pulse-stretching or missed pulses.

9.3 HART Verification

From a HART master, run the following sequence:

1. Command 0: Read unique identifier. Verify manufacturer code 0x005A (Siemens) and device type 0x0013 (MAG 5000 HART 5) or 0x0014 (MAG 6000).
2. Command 3: Read PV and SV. PV should be 0 with no flow; SV is totalizer A. TV and FV are totalizer B and flow percent of range.
3. Command 13: Read dynamic variables. Verify loop current matches the multimeter reading.
4. Command 14: Read PV with current and percent of range.
5. Command 48: Read additional device status. Look for bit flags indicating totalizer A overflow, totalizer B overflow, empty pipe, and out-of-range flow.
6. Command 55: Read additional device variables for electrode resistance, coil current, and EPD impedance (slots vary by DD version).

9.4 Burst Mode and Multidrop Considerations

If the meter is in burst mode, the transmitter continuously publishes HART data. This increases current loop noise and can affect the 4-20 mA signal. Disable burst mode for routine verification. If the meter is on a multidrop network (poll address 1-15), the current loop is fixed at 4 mA and cannot be used for flow transmission. Confirm the poll address is 0 for point-to-point analog + HART operation.

10. Fault Code Reference Table

During commissioning, the MAG 5000 status window may display fault (F-NN), warning (W-NN), or service (C-NN) codes. Use the table below to interpret them.

11. Sensor Compatibility and Variant Considerations

The MAG 5000 transmitter interfaces with three sensor families. The grounding and noise considerations apply to all, but the mechanical installation requirements differ.

For lined sensors (PTFE, ceramic) with non-conductive process fluids, the fluid does not provide an electrical path to ground. Grounding rings (conductive rings installed between the sensor flange and the adjacent pipe flange) are mandatory. Without them, the electrode signal has no reference and the meter drifts or reads zero. For water and other conductive fluids, the fluid itself provides the ground path and grounding rings are optional, but flange bonding is still required.

12. Verification and Commissioning Checklist

After completing the reset and diagnostic steps, walk through this checklist before returning the meter to service. Each item should be confirmed and signed off.

1. Both totalizers reset to zero. Display confirmed via HART commands 13/14 and front display.
2. With block valves closed and the line full, totalizer does not advance for 10 minutes.
3. Flow rate display reads 0.0 in current engineering units.
4. 4-20 mA loop reads 4.00 mA ±0.02 mA with no flow.
5. Electrode noise measured below 5 mV RMS at line frequency (true-RMS multimeter).
6. Grounding resistance measured below 1 Ω between sensor flange and earth ground.
7. Electrode-to-ground insulation measured above 100 MΩ at 500 V DC.
8. Empty pipe detection is enabled and calibrated (if process fluid is conductive > 5 µS/cm).
9. Low flow cut-off is at or above the noise floor; default 1.5% of Qmax minimum.
10. Damping is appropriate for process time constant (typically 5-30 s).
11. HART multidrop poll address is 0 for point-to-point, 1-15 for multidrop.
12. Operator password has been changed from factory default 1000.
13. Configuration has been uploaded to PDM as a backup file.
14. Pulse output is configured to match totalizer units.
15. Alarm relay (if used) is configured for the appropriate trigger (empty pipe, low flow, totalizer overflow).

13. Preventive Measures and Long-Term Maintenance

To prevent recurrence of the ###### and phantom-count symptoms, schedule the following in the maintenance plan.

• Monthly: verify totalizer A and B values, confirm they are within expected process range; check HART burst or poll data for the totalizer overflow bit (command 48).
• Quarterly: measure electrode resistance and ground resistance; verify EPD calibration by simulating an empty pipe if the process allows.
• Annually: perform zero calibration with the line full and the flow at a known zero (e.g., isolated block valves). The MAG 5000 auto-zero is in menu 5.1 and takes 60 s. Verify the zero after a known flow is re-established.
• After any process change (new pump, new VFD, new pipe material, new valve): re-verify grounding topology and re-check EPD calibration. VFD installation in particular introduces high-frequency common-mode noise that often requires a dedicated drive output filter.
• During plant shutdowns: inspect sensor electrodes for coating or fouling; clean per the sensor material datasheet (ceramic electrodes tolerate aggressive cleaning; PTFE liners are softer and require care).

14. Summary of the Repair Path