Rockwell Automation 1425 PowerMonitor Wireless 250 - Manual (Page 47)

Rockwell Automation Publication 1425-UM001A-EN-P - January 2012 47
Software Interface Chapter 3
Each bit of the 16 registers corresponds to a Modbus slave address. The Modbus
address is mapped to bit number as follows:
Examples:
• PowerMonitor W250 N° 25: register 16, bit 9 = 1
• PowerMonitor W250 N°16: register 16, bit 0 = 1
PC Receiver Network Channel (register 45)
The PC Receiver indicates and permits changing the channel number through
this ModBus register.
If you decide to change this parameter in the PC Receiver, the routers and end
devices (power monitors) will then scan for the PC Receiver and synchronize on
the same channel. The process of synchronizing may take several minutes.
PC Receiver Network UTC Time (registers 19…20)
The PC Receiver stores the reference time for the entire network in these
registers. Registers: 19 (MSW) and 20 (LSW) concatenate to form a 32-bit
UTC value. The value is equal to the number of seconds elapsed since January 1,
1970.
Routers and PowerMonitor W250 units will synchronize their internal real time
clocks after powerup, and thereafter at periodic intervals (2…4 minutes).
The initial synchronisation can take up to 6 minutes, depending on the network
configuration/number of hops from the PC Receiver to the PowerMonitor
W250 units.
The PC Receiver is not equipped with a battery, so the internal time is not kept
when power is removed. It is thus necessary to set the PC Receiver time
immediately after powerup.
Since time drift can be up to several seconds per day, synchronizing the PC
Receiver's time periodically with the Master application's time is necessary.
IMPORTANT As already stated, the Network Channel should not be modified except where
interference with other RF communication occurs. Please contact Rockwell
Automation support services for more information or if assistance is required.
ATTENTION: Before changing the channel number of a network, power down
all devices in any other PowerMonitor W250 network within radio range, to
prevent devices from the other network from synchronizing their channel to the
incorrect PC Receiver.