Mitsubishi Electric MELSEC iQ-R User Manual page 165

Considerations for the time synchronization function
• Before the operation of a BACnet module, set the clock data of CPU No.1.
For the setting of the clock data, refer to the user's manual of the CPU module used.
• There is a deviation in the clock data of CPU No.1 used by a BACnet module.
For the accuracy of the data, refer to the user's manual of the CPU module used.
• When a BACnet module obtains the clock data on a CPU No.1, a maximum of 1 second of delay occurs as the transfer
time.
• A time zone cannot be specified with the time synchronization function of a BACnet module because the clock data always
follows the time zone on the CPU module. When the time zone needs to be specified, set it on the CPU module.
To change the time in a CPU module
The time on a CPU module can be synchronized with the time on a BACnet device by creating a program.
The following shows a procedure to change the time in a CPU module.
(Operation of a BACnet module)
Receive a TimeSynchronization service or UTCTimeSynchronization service from another BACnet device.
(Program to be created)
 Check that the "Time setting request flag" is '1' (setting request), then read the data of day-of-week, time, date, and year to
the Device object (Un\G16 to Un\G31) in the buffer memory. (Page 261 Device object (Un\G16 to Un\G31))
 After reading data, change "Time setting request flag" to '2' (set).
 Create a program to change the time on the CPU module using the data of day-of-week, time, date, and year.
(MELSEC iQ-R Programming Manual (Instructions, Standard Functions/Function Blocks))
Precautions
• "Time setting request flag" is '1' (setting request) for one or two seconds.
• If a new TimeSynchronization service or UTCTimeSynchronization service is received while "Time setting request flag" is '1'
(setting request), the data will be discarded.
1 FUNCTIONS
1.11 Time Synchronization Function
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