Operating Instructions
LMS500 Product Family
Product description
8013796/UL20/2010-09-27 © SICK AG · Division Auto Ident · Germany · Subject to change without notice 37
Chapter 3
3.11 Data communication using messages
The LMS sends messages over the interfaces described above to communicate with a
connected host. The following functions can be run using messages:
• request for measured values by the host and subsequent output of the measured
values by the LMS
• parameter setting by the host for the configuration of the LMS
• parameters and status log querying by the host
The messages each comprise a frame (see section 3.11.1 “Frame and coding for the
messages” on page 37) and the data.
A detailed description of the different messages can be found in the annex (see
section 10.2 “Messages” on page 76).
3.11.1 Frame and coding for the messages
The data frame varies depending on the coding.
Messages with ASCII coding
The frame for the serial host interface can be configured in SOPAS ET: PROJECT TREE, LMS…,
I
NTERFACES, SERIAL, area SERIAL HOST INTERFACE.
In this way, for example, you can use two stop bytes (e.g. to end messages with CR/LF).
Messages with binary coding
Calculation of the checksum
The checksum is calculated using an XOR operator for every byte of the data, that is without
the frame.
Frame Message Frame
Code
STX Data (see section 10.2 “Messages” on page 76)ETX
Length (byte)
1 30 kB 1
Description
Start of text character ASCII coded. The length is dependent on the previous
send message.
End of text character
Tab. 7: Frame for the messages with ASCII coding
Frame Message Frame
Code
STX STX STX STX Message length Data (see section 10.2
“Messages” on page 76)
Checksum
Length (byte)
1111 4 2,495 1
Description
Start of text character Length of the data
without CS
Binary encoded. The length is
dependent on the previous
send message.
See
“Calculation of
the checksum”
further below
Tab. 8: Frame for the messages with binary coding
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