Enron Modbus

Hourly and Daily Archive Collection

Request

To request Enron History, function code 03 is used.
Request register # 701 (02BD hex) for the first history table
Request register # 702 (02BE hex) for the second table, etc.
Each record in a table is given an incrementing index number.

This command is requesting historical record with index #10 from table # 701
from slave device with address 1.

01 03 02BD 000A 5451

01: The Slave Address
03: The Function Code
02BD: history table to read from (02BD hex = 701 )
000A: record number to read (0A hex = 10 decimal)
5451: The CRC (cyclic redundancy check) for error checking.

Response

This is a typical response to the history request shown above.

01 03 14 47EAF800 479C4000 43C8EEAD 4400436B 4287FFFF B61E

01: The Slave Address
03: The Function Code
14: Data bytes to follow (0A hex = 20 decimal )
47EAF800: Date Stamp 32 bit float MMDDYY (120304.0 = Dec 3, 2004)
479C4000: Time Stamp 32 bit float HHMMSS (080000.0 = 8am)
43C8EEAD: 1st item logged 32-bit float (401.86)
4400436B: 2nd item logged 32-bit float (513.05)
4287FFFF: 3rd item logged 32-bit float (68.00)
B61E: The CRC (cyclic redundancy check) for error checking.

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