Modbus register assignment, Real-time clock, Real-time clock modbus register assignment – Rockwell Automation 1758-RTU202 DataSite Hardware User Manual User Manual
Page 51

Publication 1758-UM001D-EN-P - June 2011
Operating the Controller
51
Real-Time Clock
The real-time clock of the DataSite controller provides the time and date
independently for the operating system. The time and date remain correct
during power off. The calendar automatically manages leap years.
Real time clock can be saved into register by reading through the DataSite
function block, [CLOCK_GET]. The values for the data and time date are
stored in single registers as two-digit values.
For example the date and time, 17:32:23, 2004-07-13, would be stored as:
For example the date and time, 00:00:01, 2000-01-01, would be stored as:
Application programs that use the date and time data must ensure that the
rollover from year 99 to year 00 is accounted for in the program.
Modbus Register
Assignment
There are four internal registers in the DataSite controller:
• Coil_Register,
• State_Register,
• Input_Register,
• Hold_Register.
Coil_Register and State_Register are bit registers, every register address of
which is accorded with a binary bit.
Input_Register and Hold_Register are 16-bit registers.
The following table shows the Modbus address range of the controller.
Hour
Minute
Second
Year
Month
Day
17
32
23
04
7
13
Hour
Minute
Second
Year
Month
Day
00
00
01
00
01
01
Register name
Modbus address
Features
Coil_Register
00001-04096
1-bit
State_Register
10001-14096
1-bit
Input_Register
30001-31024
16-bit
Hold_Register
40001-49999
16-bit