User's Manual

Point to Point Operation

To demonstrate a simple point-to-point connection, with both modules in their default

state, send the “ ATD” command followed by a <CR> (carriage return or Enter Key) on

one module and then send the “ATA” command followed by a <CR> to the other

module. The “ ATD” command instructs the module to attempt to establish a wireless data

link in the Originate Mode. The “ ATA” command instructs the other module to attempt

to establish a wireless data link in the Answer mode. During the LINK process the

originating module will display “LINKING-O” The answering module will display

“ LINKING-A”. If the link is successful, the WHM900 modules will each display the

appropriate “CONNECT” result codes. After the CONNECT result codes are displayed,

the modules will be in On Line Data Mode and data transmission is now possible. The

data link between the modules is always error corrected so data will be received exactly

as it was sent. If data appears to be missing, verify that the data flow control is the same

on the Host and WHM900. The WHM900 defaults to Hardware Flow Control

(RTS/CTS). See the AT\Qn command change the modules flow control settings. If data

throughput is slow, set the Host equipment interface speed the same or higher than the

modules connect speed. The maximum DTE or Host interface speed is 57.6kbps. The

module will automatically detect and adjust to the new DTE speed upon receipt of the

next “ AT” command the module receives.

If ATS7 register time expires and no data link was completed, the module will display the

“ NO CARRIER” result code and will return to the Off Line Command Mode. If the On

Line Data Mode is interrupted, the modules will attempt to re-establish the connection.

Each attempt to re-connect will take approximately 10 seconds. The ATS18 register

determines how many times the module will attempt to re-connect. The “ NO LINK”

result code will be displayed after each failed attempt. If unable to successfully connect

after S18 times, the “ NO CARRIER” result code will be displayed and the modules will

return to the Off Line Command Mode. The module is now ready to accept more

commands.

The answering module can also be set up to automatically enter the ATA listening mode

upon power up or reset. See the S0 register for more information.