Data message - RSI51

RSI51 Installation Manual

Document code
M211863EN
Revision
B
Language
English (United States)
Product
RSI51
Document type
User guide

Data message format

<SOH><SID><STX><TAB>xx<TAB>y<TAB>z<TAB><CRC16 %04d><ETX><CR><LF>
Name Description
<SOH><SID><STX> Message header, where <SID> identifies individual RSI51 units. For example, 1A.
<TAB>xx<TAB>y<TAB>z<TAB>

Message data:

  • xx = Runway light intensity value
  • y = Runway-in-use 1 value
  • z = Runway-in-use 2 value
<CRC16 %04d>

Message checksum:

  • Initial value = FFFF
  • Invert result bits = Yes
  • Format = Hex
  • Polynomial = 0x1021
  • Bit reverse CRC used = No
<ETX><CR><LF> Message trailer

Data message characteristics

Property Value
Default send interval 10 s
Polling command <CR><SYN>*A<CR><ENQ><SID><CR>

Example of data message

In the following example, 12 ... 48 VDC voltage signal goes through terminal block 6, which gives a runway light intensity value 16. The voltage signal also goes through terminal block 11, and the runway-in-use value 1 indicates that runway 1 is active. This example does not include a checksum.

<SOH>1A<STX><TAB>16<TAB>1<TAB>0<TAB><ETX><CR><LF>

Starting from AviMet version 7.4, the message must include a CRC16 checksum. The following example shows the same message with the checksum.

<SOH>1A<STX><TAB>16<TAB>1<TAB>0<TAB>38B2<ETX><CR><LF>

To ensure compatibility with the older versions of AviMet and Midas IV, you can select between the standard message format and the extended format which includes the checksum. The extended format is enabled with a parameter.

With the correct message format, AviMet can parse the data and calculate the correct Runway Visual Range (RVR) value.