Keyence FD-Q + LoRaWAN Logger

Manufacturer ultrasonic sensor: Keyence Corporation
Manufacturer Logger: HSLU T&A IGE LAES
Product: FD-Q Series

The Keyence FD-Q ultrasonic flow sensor can get extended with a self-made LoRaWAN-capable ESP-based module. The module measures flow from the Keyence sensor via the 4-20mA signal and captures supply/return temperatures with PT100 sensors for thermal power and energy calculation.

Specifications
System Architecture
Documents
Ordering Info
1. Complete Kit
Calibration
1. 2-Point Calibration (4-20mA Signal)
Optional Settings
Payload Decoder
1. Payload Structure (17 Bytes)
Downlink Commands (Port 10)
Troubleshooting

Specifications

Indoor device
Built-in sensors:
- Water Flow via Keyence [l/min] via 4-20mA
- 2× Temperature PT100 4-Wire (Supply/Return) [°C]
Calculated values:
- Cumulative Volume [m³]
- Thermal Power [kW]
- Cumulative Energy [kWh]
Pipe diameter: Keyence model dependent
Power Supply: 24 VDC (Keyence, LoRa-Module gets 5V DC via a step down converter)
LoRaWAN version: 1.0.3
LoRaWAN device class: C
Display: 200×200 px E-Paper

System Architecture

┌─────────────────┐         ┌──────────────────────┐
│   Keyence FD-Q  │  4-20mA │   LoRaWAN Logger     │   LoRaWAN
│   Flow Sensor   │────────▶│   (M5Stack)          │──────────▶ TTN
│   (Clamp-On)    │         │   - Flow Reading     │
└─────────────────┘         │   - 2× PT100 Temp    │
                            │   - Energy Calc      │
┌─────────────────┐         │   - Display          │
│ PT100 Supply    │────────▶│   - NVS Storage      │
└─────────────────┘         └──────────────────────┘
┌─────────────────┐         
│ PT100 Return    │────────▶
└─────────────────┘         

Key Features:

Non-invasive flow measurement (ultrasonic clamp-on)
Precise 4-wire PT100 temperature sensors
Persistent counters (survive power loss)
Local E-Paper display
Remote configuration via LoRaWAN downlinks
2-point calibration for 4-20mA signal

Documents

Ordering Info

Complete Kit

Component	Type	Qty	Price (approx.)
Keyence FD-Q	FD-Q10C (DN20-40)	1	model dependent, not included
M5Stack Core Ink	K048	1	CHF 45.-
RAK3172 Module	LoRaWAN Breakout	1	CHF 25.-
4-20mA Unit	M5Stack AIN4-20mA	1	CHF 15.-
MAX31865	PT100 Amplifier	2	CHF 30.-
PT100 Sensors	4-wire, Class A	2	CHF 40.-
Enclosure	DIN-rail mountable	1	CHF 25.-
Cables	Various	-	CHF 20.-
TOTAL			~CHF 175.-

Calibration

2-Point Calibration (4-20mA Signal)

Why needed?

Compensates tolerances in current loop

Procedure:

Set Keyence to Test Mode:
- Keyence Menu: Enable Test Mode
- Set output to 4.00 mA (Min)
Start Calibration on Logger:
- Hold BTN_MENU for 2 seconds → Settings
- Navigate to Calibration
- Press BTN_MENU
Capture 4mA Point:
- Wait for stable reading (~4.0 mA)
- Press BTN_MENU → value saved
Capture 20mA Point:
- Set Keyence output to 20.00 mA (Max)
- Wait for stable reading (~20.0 mA)
- Press BTN_MENU → value saved
Done:
- Display shows “DONE!” with calibration values
- Values stored in NVS (permanent)
- Disable Keyence Test Mode

Optional Settings

Change TX Interval (Transmission Frequency)

Local (via Display):

Settings → TX Interval
Set value (1-240 minutes)
Save

Remote (LoRaWAN Downlink):

Port: 10
Payload: 01 0F  (15 minutes)
         01 1E  (30 minutes)
         01 3C  (60 minutes)

Set Energy Mode (Heating/Cooling)

Local:

Settings → Energy Mode
Select HEAT or COOL
Save

Effect:

HEAT: ΔT = T_Supply - T_Return (positive for heating)
COOL: ΔT = T_Return - T_Supply (positive for cooling)

⚠️ Changing mode resets volume and energy counters!

Reset Counters

Local:

Settings → Reset Counters

Remote:

Port: 10
Payload: 02

Payload Decoder

function decodeUplink(input) {
  var bytes = input.bytes;
  
  if (bytes.length !== 17) {
    return { errors: ["Invalid payload length"] };
  }
  
  // Type and Temperature Flow (10-bit)
  var type = (bytes[0] >> 4) & 0x0F;
  var t_fl_raw = ((bytes[0] & 0x0F) << 6) | ((bytes[1] >> 2) & 0x3F);
  
  // Temperature Return (10-bit)
  var t_rt_raw = ((bytes[1] & 0x03) << 8) | bytes[2];
  
  // Flow (l/min)
  var flow_raw = (bytes[3] << 8) | bytes[4];
  var flow = flow_raw / 10.0;
  
  // Volume (Liters to m³)
  var volume_L = (bytes[5] << 24) | (bytes[6] << 16) | (bytes[7] << 8) | bytes[8];
  var volume_m3 = volume_L / 1000.0;
  
  // Power (Watts to kW)
  var power_W = (bytes[9] << 16) | (bytes[10] << 8) | bytes[11];
  var power_kW = power_W / 1000.0;
  
  // Energy (Wh × 10 to kWh)
  var energy_raw = (bytes[12] << 24) | (bytes[13] << 16) | (bytes[14] << 8) | bytes[15];
  var energy_Wh = energy_raw / 10.0;
  var energy_kWh = energy_Wh / 1000.0;
  
  // Flags
  var flags = bytes[16];
  var energy_mode = (flags & 0x01) ? "Cooling" : "Heating";
  var sensor_loc = (flags & 0x02) ? "Return" : "Flow";
  
  // Temperature conversion (1023 = error)
  var t_fl = (t_fl_raw === 1023) ? null : t_fl_raw / 10.0;
  var t_rt = (t_rt_raw === 1023) ? null : t_rt_raw / 10.0;
  
  return {
    data: {
      type: type,
      flow_lmin: (flow_raw === 65535) ? null : flow,
      volume_m3: (volume_L === 0xFFFFFFFF) ? null : volume_m3,
      temp_supply_C: t_fl,
      temp_return_C: t_rt,
      power_kW: (power_W === 0xFFFFFF) ? null : power_kW,
      energy_kWh: (energy_raw === 0xFFFFFFFF) ? null : energy_kWh,
      energy_mode: energy_mode,
      sensor_location: sensor_loc
    }
  };
}

Payload Structure (17 Bytes)

Byte	Description	Unit	Format
0	Type + Temp Flow [9:6]	-	uint8
1	Temp Flow [5:0] + Temp Return [9:8]	-	uint8
2	Temp Return [7:0]	-	uint8
3-4	Flow × 10	l/min	uint16 BE
5-8	Volume	Liters	uint32 BE
9-11	Power	Watts	uint24 BE
12-15	Energy × 10	Wh	uint32 BE
16	Flags (Mode/Location)	-	uint8

Invalid Value Indicators:

Temperature: 1023 (0x3FF)
Flow: 65535 (0xFFFF)
Volume: 4294967295 (0xFFFFFFFF)
Power: 16777215 (0xFFFFFF)
Energy: 4294967295 (0xFFFFFFFF)

Downlink Commands (Port 10)

CMD 0x01: Set TX Interval

Byte 0: 0x01
Byte 1: Interval in minutes (1-240)

Examples:
  01 05  → 5 minutes
  01 0F  → 15 minutes
  01 1E  → 30 minutes

Response: 81 [Interval]

CMD 0x02: Reset Counters

Byte 0: 0x02

Response: 82
Note: Sends uplink after reset

CMD 0x05: Query Configuration

Byte 0: 0x05

Response (5 bytes):
  Byte 0: 0x85
  Byte 1: TX Interval (min)
  Byte 2: Flags (Energy Mode, Sensor Location)
  Byte 3: Flow Max / 10
  Byte 4: Reserved (0x00)

Troubleshooting

“Join FAIL”

Check LoRaWAN credentials (DevEUI/AppEUI/AppKey)
Verify gateway coverage (RSSI > -120 dBm)
Check antenna connection
Auto-retry every 60 seconds

“Sensor Err” on Display

Check 4-20mA wiring (must be 3-22 mA range)
Verify Keyence power supply
Check PT100 connections (4-wire)
Read Serial Monitor for details

No Display

Check 5V power supply (min. 1A)
Verify PWR button is bridged
Press any button to wake from standby

Display Stays in Standby

Press any button to wake
Standby activates after 60s inactivity