Manual

Rockwell Automation Publication 1425-UM001A-EN-P - January 2012 13
PowerMonitor W250 Unit Overview Chapter 1
Wireless Network Description
The PowerMonitor W250 unit communicates with the PC Receiver node by
using a self-configuring, wireless mesh network. Node IDs (addresses) are
programmed at the factory and usually do not need to be changed. Please contact
Rockwell Automation for assistance if you need to change the node ID of a
device.
In a wireless mesh network, messages may be received and retransmitted by
several devices, depending on the design and layout of the network. Each wireless
retransmission between the power monitor and the PC Receiver through one or
more Routers is called a ‘hop’. When operating, the network automatically selects
the path with the least hops through routers if it is available.
Strategies to design the wireless network to increase robustness and overcome
challenges presented by the environment are discussed in Chapter 2
, Hardware
Installation.
Each PowerMonitor W250 unit and the PC Receiver are equipped with a radio
module. The PC Receiver buffers in its RAM the metering values received from
the power monitors. The measurement values of the PowerMonitor W250 unit
are buffered in the PC Receiver's RAM.
When a Modbus master station reads data from PowerMonitor W250 registers,
it reads the buffered values from the PC Receiver.
However, when a Modbus master station transmits a command to a power
monitor, the command is forwarded to the power monitor. A delay of 2…4
minutes may occur until the PC Receiver transmits the response message.
Table 8 - Wireless Router Status Indicators
Indicator Status Description
PWR ON Power ON.
OFF No power.
RF Activity Flashing Router detects RF activity. The RF activity indicator will flash
when detecting valid packets (packets destined for device)
and may also flash when detecting invalid packets (packets
destined for other devices) or environmental noise. Only
valid packets are processed by the device.
OFF No RF activity detected.
STS ON Solid Green Device has established two or more connections with other
devices.
Blinking The router has established a single connection; additional
routers may be needed to increase robustness.
OFF The router is not on the network: additional routers are
needed for this device to connect to the network.