Operating Manual

IRS31Pro-UMB Operating Manual V10 / 01.2020
G. Lufft Mess- und Regeltechnik GmbH 47
<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).
18.3.2 Addressing with Class ID and Device ID
Addressing takes place by way of a 16 bit address. This breaks down into a Class ID and a Device ID.
Address (2 bytes = 16 bits)
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
9 IRS31Pro-UMB Road Sensor 1 – 255 Available
15 Master / 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.
18.3.3 Example for Creating Addresses
If, for example, you want to address an IRS31Pro-UMB device with the device ID 001, this takes place as
follows:
The class ID for IRS31Pro-UMB is 9d = 9h
The device ID is e.g. 001d = 01h
Putting the class and device IDs together gives the address 9001h (36865d).
18.3.4 Example of a Binary Protocol Request
If, for example, an IRS31Pro-UMB device with the device ID 001 is to be polled from a PC for the current
road surface temperature, this takes place as follows:
Sensor:
The class ID for the IRS31Pro-UMB is 9 = 9h
The device ID is 001 = 01h
Putting the class and device IDs together gives a target address of 9001h.
PC:
The class ID for the PC (master unit) is 15 = Fh
The PC ID is e.g. 001d = 01h
Putting the class and device IDs together gives a sender address of F001h.
The length <len> for the online data request command 4d = 04h.
The command for the online data request is 23h.
The version number of the command is 1.0 = 10h.
The channel number is in <payload>; as can be seen from the channel list (page 44), the current road
surface temperature in °C in channel 101d = 0065h.
The calculated CRC is 85DCh.
The request to the device:
SOH <ver> <to> <from> <len> STX <cmd> <verc> <channel> ETX <cs> EOT