User's Manual

10
Wireless Data Link Options
The WHM900 is capable of establishing different types of wireless data links. The three
most common methods are described below. Review these choices to determine which
best fits your application. The mode of operation is determined by issuing specific “AT”
commands to the module. These “AT” commands are also used to select the speed,
frequencies, transmit levels and many other features the WHM900 RF module offers.
Point-to-Point Operation - This method allows the user to set-up single or multiple point-
to-point locations by setting different channel IDs, frequencies, and speeds. This method
requires writing software to communicate to each module individually and determine
when to enter the online mode by issuing specific “AT” commands to the module.
Checking the modules I/O signals or result codes can monitor the current status of each
location.
Auto Link Operation - This feature forces the two modules to automatically maintain a
point-to-point connection. If a power outage were to occur or if the link was lost due to
temporary interference, the modules will detect the lost data link and automatically
establish a new wireless data link.
Point to Multi-Point Broadcasting – This mode allows for a Master module to broadcast
data to multiple remote Slave modules. The host software will control all data flow
between the masters and slaves. This method is sometimes referred to as Polling.