Chapter 4 Communication Protocol
Operating Manual for Communicating Area Sensor
4-14
Example : The product to be used is AS-BH028-C with communication format of 38,400bps, RTU is 8, N,
1, and data is selected to be every beams shading state, in order to obtain a fixed scan of 100Hz.
1) Beam scan time Equals 4.5msec, according to Table 4-1.
2) Data upload time: Total uploaded Bytes (Table 4-2) multiplied by upload time of every byte (Table 4-
3).
Equals 9 x 260.4usec, or around 2.3msec.
3) Delay time: 100Hz equals 10msec, minus 4.5msec, minus 2.3msec, and still requires delay of
3.2msec.
Delay time 1 can be set at 32, and delay time 2 is 0.
Alternately, delay time 1 can be set at 12, and delay time 2 at 2.
Description of automatic upload data content
1. The uploaded data is set to be (008CH) = 0, indicating the non-shading/shading state of every beam;
length will depend on the number of beams. The state of every beam is expressed by 1 bit. 1
represents shading/0 represents non-shading. Take RTU as an example:
Data
ID
1
2
3
4
5
…
N + 3
N + 4
N + 5
Item
Device
address
Function
code
Returned
data and
byte
count N
Beams
1-8
Beams
9-16
…
-8xN
beam
CRC
low
byte
CRC
high
byte
0x01
0x03
0x04
Data 1 Data 2
Data N 0xFA
0x33
Returned data and byte count
Bit
7
6
5
4
3
2
1
0
Returned data(008CH) = 0
Byte count = N
Data 1-N
Bit
7
6
5
4
3
2
1
0
Corresponding
beam
Low beam
High beam
Full non-
shading state
0
0
0
0
0
0
0
0
Full shading
state
1
1
1
1
1
1
1
1
2. The uploaded data is set at (008CH) = 1, indicating that the content is composed of the following 4
pieces of data: First shading beam; final shading beam; total shading number; and total shading
length (cm). Take RTU as an example:
Data
ID
1
2
3
4
5
6
7
8
9
Item Device
address
Function
code
Returned
data and
byte
count
First
shading
beam
Final
shading
beam
Total
shading
number
Total
shading
length
(cm)
CRC
low
byte
CRC
high
byte
0x01
0x03
0x14
0x00
0x00
0x00
0x00
0xFA
0x33
