User's Manual

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© - KYMATI GmbH – 2020
KY.MAN.0105 (4.0) KY-LOC 1D.02.01 User Manual
Doc.- No.: KY.MAN.0105
Version: 4.0
Date: 17.05.2021
Page: 29 of 43
7 Interface Description
There are two possibilities to communicate with the device, either through RS-485 or
Ethernet.
RS-485 (TIA / EIA-485-A)
The RS-485 is a unidirectional 2 wire interface, with cable lengths up to 100m. The wires
should have a termination Resistor of 120 Ω at both ends.
RS-485 Parameters
RS-485 Values
Transmission Rate
921.6 KBaud
Start Bit
1 (logical low)
Stop Bit
1 (logical high)
Parity Bits
None
Data Bits
8
Flow Control
None
Table 4: RS-485 SW Interface Configuration
To communicate with KYMATI Radars through a RS-485 connection, messages need to be
encoded or decoded using byte stuffing into/from a protocol frame as shown in the Figure
below.
Figure 1: Protocol Description
The byte 0x7E is used to detect the beginning and 0x7F is used to detect the end of valid
protocol frame. In this setting we use the byte stuffing technique based on the following
transition table:
Original Byte
Stuffed Byte Sequence
0x7E
0x7D 0x5E == 0x7D (0x7E XOR 0x20)
0x7D
0x7D 0x5D == 0x7D (0x7D XOR 0x20)
0x7F
0x7D 0x5F == 0x7D (0x7F XOR 0x20)
Table 5: Transition table
During encoding, we search for the original bytes listed in the transition table inside a given
message and replace it with the stuffed byte sequence. The encoding can be implemented