Lufft SHM31 User Manual

UMB communication
Snow depth sensor SHM 31, V2.1 39
10000
vin monitor
float32
V
10001
15V monitor
float32
V
Table 15: Measuring channels starting from 5000
9.3. Communication in binary protocol
In this case, communication with the snow depth sensor takes place using the RS485 connection
e.g. with UMB ConfigTool.NET. Please refer to the UMB protocol manual, if desired, for a general
description of communication in the UMB binary protocol over the RS485 interface. The
description of the UMB protocol can be downloaded from the Lufft website at www.lufft.com.
9.3.1. Data frame
The data frame is constructed as follows:
1
2
3 - 4
5 - 6
7
8
9
10
11 ... (8 + len)
optional
9 + len
10 + len
11 + len
12 + len
SOH
<ver>
<to>
<from>
<len>
STX
<cmd>
<verc>
<payload>
ETX
<cs>
EOT
SOH
Control character for the start of a frame (01h); 1 byte
<ver>
Header version number, e.g.: V 1.0 <ver> = 10h = 16d; 1 byte
<to>
Receiver address; 2 bytes
<from>
Sender address; 2 bytes
<len>
Number of data bytes between STX and ETX; 1 byte
STX
Control character for the start of payload transmission (02h); 1 byte
<cmd>
Command; 1 byte
<verc>
Version number of the command; 1 byte
<payload>
Data bytes; 0 – 210 bytes
ETX
Control character for the end of payload transmission (03h); 1 byte
<cs>
Check sum, 16 bit CRC; 2 bytes
EOT
Control character for the end of the frame (04h); 1 byte
Control characters: SOH (01h), STX (02h), ETX (03h), EOT (04h).
9.3.2. Addressing with class ID and device ID
Addressing is performed using a 16-bit address. This is split into a class ID and a device ID.
Address (2 bytes = 16 bit)
Bits 15 – 12 (upper 4 bits)
Bits 11 – 8
(middle 4 bits)
Bits 7 – 0 (lower 8 bits)
Class ID (0 to 15)
Reserve
Device ID (0 – 255)
0
Broadcast
0
Broadcast
11
SHM31 Snow Depth Sensor
1 - 255
Available
15
Master or control devices
ID = 0 is provided as broadcast for classes and devices. Thus, it is possible to transmit a broadcast
on a specific class. However this only makes sense if there is only one device of this class on the
bus; or in the case of a command, e.g. reset.
9.3.3. Example of creating addresses.
If an SHM 31 sensor is to be addressed with the device ID 001, this is done as follows:
The class ID is: 11d = Bh; the device ID is: 001d = 001h
Combining the class ID and the device ID creates the address B001h (45057d).
9.3.4. Example of a binary protocol query
If, for example, a sensor with the device ID 001 is polled from a PC for the current snow depth,
this takes place as follows:

Lufft SHM31 Specifications

General

Housing material	Plastic
Humidity Range	0% to 100% RH
Humidity Accuracy	±2% RH
Mounting	Wall
Measurement Parameters	Temperature, Humidity
Output	RS-485
Power Supply	12 VDC to 24 VDC

Summary

Read Before Commissioning

Safety Instructions

Provides essential safety precautions for assembly, operation, and handling of the sensor.

Laser Safety and Classification

Details laser safety Class 2 compliance and exposure guidelines to prevent eye damage.

Item and Technical Data

Technical Data

Presents detailed specifications including measuring parameters, interfaces, operating conditions, and dimensions.

Device Description and Operation

Measurement Method Principles

Explains the phase measurement method utilizing laser pulses for distance measurement.

Assembly and Commissioning Introduction

Guides on sensor mounting, alignment, and initial setup procedures including zero measurement.

Sensor Assembly

Assembly Procedures

Details the physical mounting of the sensor on a mast using provided clamps and alignment procedures.

Device Connections

Connector Pin Assignment

Maps the interface cable cores to specific pins on the SHM 31 connector.

Data Interfaces

Lists the available communication interfaces: RS485, SDI-12, and RS232.

Commissioning the Sensor

Important Commissioning Information

Highlights key points for successful commissioning, including software usage and laser safety.

UMB ConfigTool.NET Setup

Introduces the UMB ConfigTool.NET software for sensor configuration, firmware updates, and data acquisition.

UMB-ASCII 2.0 Communication

Communication Syntax

Defines the grammatical structure and components of UMB-ASCII 2.0 data telegrams.

UMB Communication Protocols

Measuring Channels Overview

Lists the available UMB channels with their measured variables and units.

Binary Protocol Communication

Explains how to communicate using the UMB binary protocol, including data frames and addressing.

UMB Binary Protocol Status and Error Codes

Lists and explains status and error codes encountered in UMB binary protocol communication.

SDI-12 Mode Communication

SDI-12 Settings and Configuration

Guides on configuring the sensor for SDI-12 communication via ConfigTool.NET or ASCII commands.

Query Measured Value Parameters

Describes the command for querying measured value parameters and their codes.

Switching Commands

Introduces manufacturer-defined SDI-12 commands used to trigger specific procedures.

Calibrate Offset and Angle

Describes the command to start a process for determining and setting distance and angle offsets.

Parameter Setting Commands

Introduces commands for reading and setting sensor parameters in SDI-12 mode.

Modbus Mode Communication

Modbus Functions Overview

Lists the implemented Modbus functions applicable to the SHM 31-UMB.

Read Input Registers Function (0x04)

Details the function for reading measured values and status information via input registers.

Signal Quality Check

Application of Target Plates

Explains how to use target plates to check the sensor's signal intensity and reflectivity response.

Service, Maintenance, and Support

Firmware Update Procedure

Guides on how to update the sensor's firmware using the UMB ConfigTool.NET software.

Troubleshooting Sensor Faults

Lists common errors, their possible causes, remedies, and specific error codes.

Technical Support and Repair

Offers contact information for obtaining technical assistance and repair for the sensor.