The query format for downloading an entry of a time datalog is given below. Maximum number of register the user
can access in 1 query are limited by 64 and corresponding to it maximum byte count is 128. The byte count should
be logging parameter count multiplied by 4 and added to 8, where 8 is the byte count for date and time (4 bytes x 2
parameters).
(logging parameter count x 4) + (2 x 4)
e.g.
if logging parameter count is 10
byte count = (10 x 4) + 8 = 48 (4 bytes per parameter)
number of registers = (10 x 2) + (2 x 2) = 24 (2 registers per parameter)
Starting address will be 01,CA for time datalog.
The entry number of the desired log need to be converted to IEEE format and sent as 4 bytes.
Query Format for Downloading the Time based datalog
Description Decimal Value Hex Value
Dev Addr 3 03
Func Code 16 10
Start Addr Hi 01
Start Addr Lo CA
No of Reg Hi 00 00
No of Reg Lo 14 0E
Log Download Bytes 28 1C
Entry No Reg 1 Hi
25
41
Entry No Reg 1 Lo C8
Entry No Reg 2 Hi 00
Entry No Reg 2 Lo 00
CRC Lo CC
CRC Hi A4
Query example:
If a user wants to download 5 parameters logged at entry
number 25, the query will be as following (Assuming device
address 3). All the data in query is represented in hexadecimal
float.
03,10, 01, CA,00,0E,1C,41,C8,00,00,CC,A4
03 is device address;
10 is function code;
01 CA is the address that lets the user access the time datalog;
00 0E is number of registers to be accessed (actual parameter
count x 2+4);
1C is number of bytes to be accessed;
41 C8 00 00 is entry number converted to hex;
CC A4 is CRC calculated on query.
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