5.4. SDI-12 Protocol

Protocol Overview

The FX200 flow meter supports communication via the SDI-12 (Serial Data Interface at 1200 baud) protocol. The instrument responds to standard SDI-12 measurement commands by returning measured surface velocity and related data, and, in addition to standard measurement commands, the device implements a set of custom SDI-12 commands that allow users to read and modify internal configuration parameters, retrieve diagnostic information, and execute specific service operations such as restoring factory default settings.

In the command tables below, a represents the device address. CR and LF denote carriage return / line feed pair which is sent at the end of each response. The response contains no space character – in the table below the spaces are inserted between response elements to improve readability only.

Standard SDI-12 Commands

Device Address Query

Device will identify by returning its SDI-12 address. The factory default address is 0.

Request	Response	Example
?!	a CR LF	→ ?! ← 0

Ping Sensor

The device will return its address if the address in the request matches the device address. This command is used to verify that the device is active, at a given address, and responding to requests.

Request	Response	Example
a!	a CR LF	→ 0! ← 0

Change Address

The device will reconfigure to change its SDI-12 device address, and will respond with the new address. All subsequent requests to the device should be addressed to the new address. Take care when changing address, if improperly set on multi-sensor bus this can cause address collision.

Request	Response	Example
aAb!	b CR LF	→ 0A5! ← 5

Get Device Identification

The device will respond with its identification information:

• 14 = SDI protocol version 1.4

• GEOLUX  FX200 = device name, with two space characters between

• fff = current firmware version, one space character before

Request	Response	Example
aI!	a14GEOLUX  FX200 fff CR LF	→ 0I! ← 014GEOLUX  FX200 105

Verify Device

This command is executed in two steps. First, the master sends the command aV! to initiate the verification procedure. The device responds with a standard SDI-12 service request indicating that after 000 seconds one value will be available for retrieval.

The master must then issue the aD0! command to read the available value. The device responds with a single measurement representing the instrument’s operational status:

• 0 = not ready

• 1 = ready

Request	Response	Example
aV! aD0!	a00001 CR LF as CR LF	→ 0V! ← 000001 → 0D0! ← 01

Perform Measurement

This command instructs the instrument to start a measurement cycle. Upon receiving aM!, the device immediately responds with the required warm-up time in seconds and the total number of measurement values that will be available once the measurement is completed.

After the specified warm-up time has elapsed, the master should retrieve the measurement results using the aD0!, aD1!, etc. commands as needed, until all reported values have been read.

If a CRC checksum is required to ensure data integrity, the aMC! command shall be used instead of aM!. This command functions identically to aM!, but the instrument appends a CRC checksum to each data response. The checksum in the response allows the master to verify the consistency and correctness of the transmitted values.

The Geolux FX200 returns 8 values, in the following order:

1. Discharge, in selected measurement unit,

2. Water level, in selected measurement unit,

3. Distance to water, in selected measurement unit,

4. Absolute surface velocity, in selected measurement unit,

5. Total volume, in selected measurement unit,

6. Flow direction flag (1 incoming, -1 outgoing, 0 no flow),

7. Surface velocity SNR, in dB,

8. Water level SNR, in dB.

The grouping of measurement values in responses to the aD0!, aD1!, aD2!, etc., commands does not necessarily follow the structure shown in the example above. The example is provided for illustration purposes only. In accordance with the SDI-12 protocol, the instrument may distribute the returned values across one or more data responses depending on the total length of the response string. Each SDI-12 response is limited in length, so the device dynamically groups values to fit within this constraint.

Request	Response	Example
aM! or aMC! aD0! aD1!	asss8 CR LF a discharge level dist vel CR LF a volume dir svrsnr levsnr CR LF	→ 0M! ← 00158 … after 15 seconds … → 0D0! ← 0+1.023+1.12+2.21+0.54 → 0D1! ← 0+10.212+1.0+48.0+42.0

Measure System Status

This command will instruct the instrument to measure and return system status. The measurements will be immediately available.

If a CRC checksum is required to ensure data integrity, the aMC1! command shall be used instead of aM1!. This command functions identically to aM1!, but the instrument appends a CRC checksum to each data response. The checksum in the response allows the master to verify the consistency and correctness of the transmitted values.

The Geolux FX200 returns 5 values, in the following order:

1. Forward tilt angle, in degrees,

2. Side tilt angle, in degrees,

3. Device temperature, in °C,

4. Device relative humidity, in %,

5. Device error status bitmask:

   Bit 0 = forward tilt angle error

   Bit 1 = side tilt angle error

   Bit 2 = radar co-processor update failed

   Bit 3 = velocity radar co-processor not responding

   Bit 4 = radar co-processor needs to be updated

   Bit 5 = tilt sensor is not working

   Bit 6 = level radar co-processor not responding

   Bit 7 = DFP data corrupt, needs reset

   Bit 8 = standby mode is active

   Bit 9 = radar is initializing

The grouping of measurement values in responses to the aD0!, aD1!, aD2!, etc., commands does not necessarily follow the structure shown in the example above. The example is provided for illustration purposes only. In accordance with the SDI-12 protocol, the instrument may distribute the returned values across one or more data responses depending on the total length of the response string. Each SDI-12 response is limited in length, so the device dynamically groups values to fit within this constraint.

Request	Response	Example
aM! or aMC! aD0! aD1!	asss5 CR LF a fwdtilt sidetilt CR LF a temp rhum status CR LF	→ 0M! ← 00005 … immediately available … → 0D0! ← 0+1.0+0.0 → 0D1! ← 0+22.4+39.0+0

Perform Concurrent Measurement

The aC! command operates similarly to the previously described aM! command, with the key difference being that it enables concurrent measurements. After receiving aC!, the instrument responds with the required processing time and the number of values that will be available.

Unlike aM!, the instrument does not hold the SDI-12 bus during the measurement process. This allows other SDI-12 devices on the same bus to perform measurements simultaneously. Once the indicated processing time has elapsed, the master can retrieve the results using the aD0!, aD1!, etc., commands, in the same manner as for aM!.

In accordance with the SDI-12 specification for concurrent commands, the response to aC! uses two digits to indicate the number of measurement values that will be returned.

If a CRC checksum is required to ensure data integrity, the aCC! command shall be used instead of aC!. This command functions identically to aC!, but the instrument appends a CRC checksum to each data response. The checksum in the response allows the master to verify the consistency and correctness of the transmitted values.

The grouping of measurement values in responses to the aD0!, aD1!, aD2!, etc., commands does not necessarily follow the structure shown in the example above. The example is provided for illustration purposes only. In accordance with the SDI-12 protocol, the instrument may distribute the returned values across one or more data responses depending on the total length of the response string. Each SDI-12 response is limited in length, so the device dynamically groups values to fit within this constraint.

Request	Response	Example
aC! or aCC! aD0! aD1!	asss08 CR LF a discharge level dist vel CR LF a volume dir svrsnr levsnr CR LF	→ 0C! ← 001508 … after 15 seconds … → 0D0! ← 0+1.023+1.12+2.21+0.54 → 0D1! ← 0+10.212+1.0+48.0+42.0

Identify Parameter (SDI-12 Version 1.4)

The FX200 implements the SDI-12 version 1.4 Identify Parameter command. This command returns descriptive information about a measurement parameter supported by the instrument.

The command format is aIM_nnn!, where a is the SDI-12 device address and nnn is the three-digit parameter number. The FX200 supports parameter numbers 001 through 008, corresponding to the eight values returned by the standard measurement command.

The response format is:

• a = device address

• name = parameter name

• unit = parameter unit

Request	Response	Example
aIM_nnn!	a,name,unit; CR LF	→ 0IM_001! ← 0,discharge,m3/s; → 0IM_002! ← 0,level,m; → 0IM_003! ← 0,distance,m; → 0IM_004! ← 0,velocity,mms; → 0IM_005! ← 0,volume,m3; → 0IM_006! ← 0,direction, ; → 0IM_007! ← 0,SNR,dB; → 0IM_008! ← 0,levelSNR,dB;

Custom (Extended) SDI-12 Commands Specific for FX200

Maximum Velocity Threshold

Sets / gets the upper bound for valid surface velocity measurements. Velocity readings above this threshold are rejected. The numeric value parameter is interpreted in the unit set by aXGMVU!. See Maximum Velocity for the detailed setting description.

Mode	Request	Response	Example
Get	aXGMVL!	a value CR LF	→ 0XGMVL! ← 016
Set	aXGMVL value!	a value CR LF	→ 0XGMVL+15! ← 015

Maximum Velocity Unit

Gets / sets the physical unit used by aXGMVL! command. See Maximum Velocity for the detailed setting description. The units are represented by the numerical value as follows:

• 0 = mm/s,

• 1 = m/s,

• 2 = mph,

• 3 = km/h,

• 4 = ft/s,

• 5 = ft/min,

• 6 = cm/s.

Mode	Request	Response	Example
Get	aXGMVU!	a value CR LF	→ 0XGMVU! ← 01
Set	aXGMVU value!	a value CR LF	→ 0XGMVU+6! ← 06

Direction Filter

Gets / sets the direction filter configuration. See Direction Filter for the detailed setting description.

• 0 = measure both directions

• 1 = incoming flow only

• 2 = outgoing flow only

Mode	Request	Response	Example
Get	aXGDFT!	a value CR LF	→ 0XGDFT! ← 00
Set	aXGDFT value!	a value CR LF	→ 0XGDFT+2! ← 02

SNR Threshold

Gets / sets the SNR threshold value. See SNR Threshold for the detailed setting description.

Mode	Request	Response	Example
Get	aXGSTH!	a value CR LF	→ 0XGSTH! ← 00
Set	aXGSTH value!	a value CR LF	→ 0XGSTH+2! ← 02

Filter Length

Gets / sets the number of seconds used for internal smoothing. Higher values reduce noise but increase response lag. See Filter Length for the detailed setting description. The valid range is between 1 and 120.

Mode	Request	Response	Example
Get	aXGFLN!	a value CR LF	→ 0XGFLN! ← 01
Set	aXGFLN value!	a value CR LF	→ 0XGFLN+20! ← 020

Discharge Output Unit

Gets / sets the unit used for the discharge value in the SDI-12 measurement response, NMEA and on Modbus output. See Discharge Output Unit for the detailed setting description. The units are represented by the numerical value as follows:

• 0 = m³/s,

• 1 = m³/h,

• 2 = L/s,

• 3 = L/h,

• 4 = ft³/s (cfs),

• 5 = gal/min,

• 6 = ML/day.

Mode	Request	Response	Example
Get	aXGDSU!	a value CR LF	→ 0XGDSU! ← 01
Set	aXGDSU value!	a value CR LF	→ 0XGDSU+3! ← 03

Water Level Output Unit

Gets / sets the unit used for the water level and distance to water values in the SDI-12 measurement response, NMEA and on Modbus output. See Water Level Output Unit for the detailed setting description. The units are represented by the numerical value as follows:

• 0 = mm,

• 1 = cm,

• 2 = mph,

• 3 = m,

• 4 = ft,

• 5 = in.

Mode	Request	Response	Example
Get	aXGLVU!	a value CR LF	→ 0XGLVU! ← 03
Set	aXGLVU value!	a value CR LF	→ 0XGLVU+2! ← 02

Velocity Output Unit

Gets / sets the unit used for the velocity value in the SDI-12 measurement response, NMEA and on Modbus output. See settings-output-unit for the detailed setting description. The units are represented by the numerical value as follows:

• 0 = mm/s

• 1 = m/s

• 2 = mph

• 3 = km/h

• 4 = ft/s

• 5 = ft/min

• 6 = cm/s

Mode	Request	Response	Example
Get	aXGUNT!	a value CR LF	→ 0XGUNT! ← 01
Set	aXGUNT value!	a value CR LF	→ 0XGUNT+0! ← 00

Beam Width

Gets / sets the radar beam width pattern. Wide beam covers a larger area; narrow beam is more focused and rejects off-axis targets. See Beam Width for the detailed setting description.

• 0 = wide

• 1 = narrow

Mode	Request	Response	Example
Get	aXGRBW!	a value CR LF	→ 0XGRBW! ← 00
Set	aXGRBW value!	a value CR LF	→ 0XGRBW+1! ← 01

Beam Position

Gets / sets the near or far measurement zone placed along the radar beam used for target detection. See Beam Position for the detailed setting description.

• 0 = near

• 1 = far

Mode	Request	Response	Example
Get	aXGBOF!	a value CR LF	→ 0XGBOF! ← 00
Set	aXGBOF value!	a value CR LF	→ 0XGBOF+1! ← 01

DFP Enable

Gets / sets the enable status of Dynamic Flow Profiler algorithm, which tracks and accumulates flow history for improved accuracy in low-flow conditions. See Dynamic Flow Profiler for the detailed setting description.

• 0 = disabled

• 1 = enabled

Mode	Request	Response	Example
Get	aXGDFP!	a value CR LF	→ 0XGDFP! ← 00
Set	aXGDFP value!	a value CR LF	→ 0XGDFP+1! ← 01

Radar Height

Gets / sets the vertical distance between the instrument and the water level reference point (gauge zero). The instrument uses this value to calculate and report the water level relative to the gauge zero. The corresponding measurement unit is set by aXGRHU!.

Mode	Request	Response	Example
Get	aXGRHG!	a value CR LF	→ 0XGRHG! ← 00
Set	aXGRHG value!	a value CR LF	→ 0XGRHG+12.11! ← 0+12.11

Radar Height Unit

Gets / sets the measurement unit used by the parameter set by aXGRHG! The valid units are:

• 0 = mm,

• 1 = cm,

• 2 = mph,

• 3 = m,

• 4 = ft,

• 5 = in.

Mode	Request	Response	Example
Get	aXGRHU!	a value CR LF	→ 0XGRHU! ← 02
Set	aXGRHU value!	a value CR LF	→ 0XGRHU+1! ← 01

Minimum Valid Distance

Gets / sets the minimum valid distance to water surface. Reflections detected closer than this distance are ignored. Use this parameter to exclude near-field returns e.g., mounting hardware, bridge elements, or other objects close to the sensor. See Minimum Distance for the detailed setting description. The corresponding measurement unit is set by aXGDU0!.

Mode	Request	Response	Example
Get	aXGDZ0!	a value CR LF	→ 0XGDZ0! ← 00
Set	aXGDZ0 value!	a value CR LF	→ 0XGDZ0+1! ← 01

Minimum Valid Distance Unit

Gets / sets the measurement unit used by minimum valid distance parameter (aXGDZ0!). See Minimum Distance for the detailed setting description. The valid units are:

• 0 = mm

• 1 = cm

• 2 = m

• 3 = ft

• 4 = in

Mode	Request	Response	Example
Get	aXGDU0!	a value CR LF	→ 0XGDU0! ← 02
Set	aXGDU0 value!	a value CR LF	→ 0XGDU0+1! ← 01

Maximum Valid Distance

Gets / sets the maximum valid distance to water surface. Reflections detected beyond this distance are ignored. Use this parameter to exclude far-field returns outside the intended measurement zone e.g., opposite bank, structures, or background targets. See Maximum Distance for the detailed setting description. The corresponding measurement unit is set by aXGDU1!.

Mode	Request	Response	Example
Get	aXGDZ1!	a value CR LF	→ 0XGDZ1! ← 030
Set	aXGDZ1 value!	a value CR LF	→ 0XGDZ1+5! ← 05

Maximum Valid Distance Unit

Gets / sets the measurement unit used by maximum valid distance parameter (aXGDZ1!). See Maximum Distance for the detailed setting description. The valid units are:

• 0 = mm

• 1 = cm

• 2 = m

• 3 = ft

• 4 = in

Mode	Request	Response	Example
Get	aXGDU1!	a value CR LF	→ 0XGDU1! ← 02
Set	aXGDU1 value!	a value CR LF	→ 0XGDU1+3! ← 03

RS-232 Baud Rate

Gets / sets the baud rate of the RS-232 serial interface. The change takes effect immediately. See RS-232 Baud Rate for the detailed setting description. The valid values for baud rates are:

• 0 = 4800

• 1 = 9600

• 2 = 14400

• 3 = 19200

• 4 = 38400

• 5 = 57600

• 6 = 115200

Mode	Request	Response	Example
Get	aXGSBD!	a value CR LF	→ 0XGSBD! ← 06
Set	aXGSBD value!	a value CR LF	→ 0XGSBD+1! ← 01

Modbus Baud Rate

Gets / sets the baud rate of the RS-485/Modbus serial interface. The change takes effect immediately. See RS-485 Baud Rate for the detailed setting description. The valid values for baud rates are:

• 0 = 4800

• 1 = 9600

• 2 = 14400

• 3 = 19200

• 4 = 38400

• 5 = 57600

• 6 = 115200

Mode	Request	Response	Example
Get	aXGMBD!	a value CR LF	→ 0XGMBD! ← 01
Set	aXGMBD value!	a value CR LF	→ 0XGMBD+6! ← 06

Modbus Device ID

Gets / sets the Modbus RTU slave address. Must be unique on the RS485 bus. See Modbus ID for the detailed setting description. The accepted value range for Modbus RTU slave address is 1 - 247.

Mode	Request	Response	Example
Get	aXGMID!	a value CR LF	→ 0XGMID! ← 01
Set	aXGMID value!	a value CR LF	→ 0XGMID+10! ← 010

Modbus Serial Line Parity

Gets / sets the serial line parity for RS-485 / Modbus connection. The change takes place immediately. See Modbus Parity for the detailed setting description. The valid values are:

• 0 = none

• 1 = odd

• 2 = even

Mode	Request	Response	Example
Get	aXGMPA!	a value CR LF	→ 0XGMPA! ← 02
Set	aXGMPA value!	a value CR LF	→ 0XGMPA+0! ← 00

Modbus Serial Line Stop Bits

Gets / sets the number of stop bits for the serial line of RS-485 / Modbus connection. The change takes place immediately. See RS-485 Stop Bits for the detailed setting description. The valid values are:

• 0 = one

• 1 = two

Mode	Request	Response	Example
Get	aXGMSB!	a value CR LF	→ 0XGMSB! ← 00
Set	aXGMSB value!	a value CR LF	→ 0XGMSB+1! ← 01

Disable NMEA Output

Gets / sets the parameter that disables NMEA sentence output on RS-232. The valid values are:

• 0 = NMEA enabled

• 1 = NMEA disabled

Mode	Request	Response	Example
Get	aXGNMA!	a value CR LF	→ 0XGNMA! ← 00
Set	aXGNMA value!	a value CR LF	→ 0XGNMA+1! ← 01

Analog Output Type

Gets / sets the which device measurement will be used to drive the analog output. The accepted values are:

• 0 = none,

• 1 = discharge,

• 2 = water level,

• 3 = distance to water,

• 4 = surface velocity,

• 5 = total volume.

Mode	Request	Response	Example
Get	aXGANU!	a value CR LF	→ 0XGANU! ← 01
Set	aXGANU value!	a value CR LF	→ 0XGANU+2! ← 02

Analog Output Minimum Value

Gets / sets the surface velocity measurement value that corresponds to the minimum output on the analog current interface (4 mA). See 4 - 20 mA Minimum Value for the detailed setting description. The measurement unit is set by aXGAU0!.

Mode	Request	Response	Example
Get	aXGAV0!	a value CR LF	→ 0XGAV0! ← 00
Set	aXGAV0 value!	a value CR LF	→ 0XGAV0+0.1! ← 00.1

Analog Output Minimum Unit

Gets / sets the measurement unit for the value set by aXGAV0! command. See 4 - 20 mA Minimum Value for the detailed setting description. The valid units depend on the output type set by aXGANU:

For discharge:

• 0 = m³/s

• 1 = m³/h

• 2 = l/s

• 3 = l/h

• 4 = cfs

• 5 = gal/min

• 6 = ML/day

For water level and distance to water:

• 0 = mm

• 1 = cm

• 2 = m

• 3 = ft

• 4 = in

For surface velocity:

• 0 = mm/s

• 1 = m/s

• 2 = mph

• 3 = km/h

• 4 = ft/s

• 5 = ft/min

• 6 = cm/s

For volume:

• 0 = m³

• 1 = l

• 2 = ftm³

• 3 = gal

• 4 = ML

Mode	Request	Response	Example
Get	aXGAU0!	a value CR LF	→ 0XGAU0! ← 01
Set	aXGAU0 value!	a value CR LF	→ 0XGAU0+4! ← 04

Analog Output Maximum Value

Gets / sets the surface velocity measurement value that corresponds to the maximum output on the analog current interface (20 mA). See 4 - 20 mA Maximum Value for the detailed setting description. The measurement unit is set by aXGAU1!.

Mode	Request	Response	Example
Get	aXGAV1!	a value CR LF	→ 0XGAV1! ← 016
Set	aXGAV1 value!	a value CR LF	→ 0XGAV1+10! ← 010

Analog Output Maximum Unit

Gets / sets the measurement unit for the value set by aXGAV1! command. See 4 - 20 mA Maximum Value for the detailed setting description. The valid units depend on the analog output type set by aXGANU.

For discharge:

• 0 = m³/s

• 1 = m³/h

• 2 = l/s

• 3 = l/h

• 4 = cfs

• 5 = gal/min

• 6 = ML/day

For water level and distance to water:

• 0 = mm

• 1 = cm

• 2 = m

• 3 = ft

• 4 = in

For surface velocity:

• 0 = mm/s

• 1 = m/s

• 2 = mph

• 3 = km/h

• 4 = ft/s

• 5 = ft/min

• 6 = cm/s

For volume:

• 0 = m³

• 1 = l

• 2 = ftm³

• 3 = gal

• 4 = ML

Mode	Request	Response	Example
Get	aXGAU1!	a value CR LF	→ 0XGAU1! ← 01
Set	aXGAU1 value!	a value CR LF	→ 0XGAU1+3! ← 03

Configure Power Management Mode (Automatic SDI-12 Sleep)

Gets / sets the automatic SDI-12 sleep mode parameter. When sleep is enabled, the device enters low-power standby between SDI-12 transactions. When disabled, the sensor runs continuously and is ready at all times. See Power Management for the detailed setting description. The valid parameters are:

• 0 = sleep enabled

• 1 = sleep disabled (continuous scanning)

Mode	Request	Response	Example
Get	aXGCON!	a value CR LF	→ 0XGCON! ← 01
Set	aXGCON value!	a value CR LF	→ 0XGCON+0! ← 00

Configure Operation Mode

Gets / sets the operation mode parameter. When the operation mode is set to standby, the device will go to standby mode. In standby mode, it will communicate on all communication interfaces, but the radar transmitters will be turned off to reduce the power, and the instrument will not be making any measurements. See Operation Mode for the detailed setting description. The accepted values are:

• 0 = off (normal operation)

• 1 = on (standby operation)

Mode	Request	Response	Example
Get	aXGMUT!	a value CR LF	→ 0XGMUT! ← 00
Set	aXGMUT value!	a value CR LF	→ 0XGMUT+1! ← 01

Configure Fixed Mounting Angle

Override measured forward angle with a fixed value (degrees). Changing this parameter will affect the reported velocity as cosine correction behaviour will be changed. Use this parameter only during tow-tank testing. Set 0 to use real measured angle. The accepted value range for fixed angle is 0 - 89.

Mode	Request	Response	Example
Get	aXGFIX!	a value CR LF	→ 0XGFIX! ← 00
Set	aXGFIX value!	a value CR LF	→ 0XGFIX+1! ← 01

Enable Wi-Fi

Enable or disable the WiFi hotspot:

• 0 = disabled

• 1 = enabled

Mode	Request	Response	Example
Get	aXGWFE!	a value CR LF	→ 0XGWFE! ← 00
Set	aXGWFE value!	a value CR LF	→ 0XGWFE+1! ← 01

Set Wi-Fi Password

Change the Wi-Fi password. This parameter is write-only. The password can contain only letters, numbers, and dash or dot character. Other characters cannot be used in the password if it is changed via SDI-12. It needs to be at least 8 characters long.

Mode	Request	Response	Example
Set	aXGWFP value!	a 1 CR LF	→ 0XGWFP+NewPassword! ← 01

Show Data on Error

Continue reporting velocity data even when angle errors are detected.

• 0 = clear velocity on error (send 0 as velocity instead of the measured value)

• 1 = keep velocity

Mode	Request	Response	Example
Get	aXGSDE!	a value CR LF	→ 0XGSDE! ← 00
Set	aXGSDE value!	a value CR LF	→ 0XGSDE+1! ← 01

LiDAR Scan Period

Gets / sets the interval between two consecutive automatic LiDAR scans of the channel cross-section, in minutes. The valid range is between 1 and 1440 minutes. This parameter is used only when the automatic LiDAR mode is enabled. See LiDAR Scan Period for the detailed setting description.

The automatic LiDAR mode and the LiDAR limit angles cannot be configured over SDI-12. Use the configuration application, the servicing protocol, or Modbus to change these settings.

Mode	Request	Response	Example
Get	aXGLSP!	a value CR LF	→ 0XGLSP! ← 015
Set	aXGLSP value!	a value CR LF	→ 0XGLSP+60! ← 060

Start Manual LiDAR Scan

Starts a single LiDAR scan of the channel cross-section. The command can be used regardless of the configured LiDAR mode. The scan takes 30 to 45 seconds to complete. If a scan is already running, the command is ignored. See Manual LiDAR Scan for the detailed description.

Request	Response	Example
aXGSCB!	a CR LF	→ 0XGSCB! ← 0

Perform Soft Reset

Restarts the device firmware. All settings are retained (stored in non-volatile memory). The device will be unresponsive for a few seconds after issuing this command.

Request	Response	Example
aXGRST!	a CR LF	→ 0XGRST! ← 0

Reset DFP

Clears all accumulated DFP history data. Use this after a significant change in site conditions or sensor placement.

Request	Response	Example
aXGRDP!	a CR LF	→ 0XGRDP! ← 0

Factory Reset

Restores all settings to their factory defaults and restarts the device. This is irreversible.

Request	Response	Example
aXGFAC!	a CR LF	→ 0XGFAC! ← 0

Totalizer Reset

Resets the accumulated total volume to zero.

Request	Response	Example
aXGRTL!	a CR LF	→ 0XGRTL! ← 0

Set Staff Gauge Reading

Takes current reading from the staff gage to automatically adjust the radar height parameter according to the given value and current measurement of the distance to water surface. The radar height measurement unit set by aXGRHG is used.

Request	Response	Example
aXGSSG value!	a CR LF	→ 0XGSSG+12.221! ← 0+12.221

Wake Up

This command wakes the device from SDI-12 sleep mode and keeps it awake for approximately 1 minute.

Use this command when the automatic SDI-12 sleep mode is enabled (set with aXGCON+0!) and temporary access to the device is required. While awake, RS-232 and RS-485/Modbus interfaces remain active, allowing a connection to be established with the PC configuration application. After the timeout period expires, the device automatically returns to sleep mode if no further activity is detected.

Request	Response	Example
aXGLWU!	a CR LF	→ 0XGLWU! ← 0