Radiometrix Ltd.

UHF FM Radio Packet Modem

page 3

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forces the RPM3B into a suspended state. Communications cannot be made with the RPM3B in this

state. WAKE/DTR pin should be pulled Low by host or connected to 0V to Enable the RPM3B.

Immediately after power up and during normal operation, the RPM3B will automatically enter standby

mode where it is waiting for a connection request from a remote RPM3B module.

While in this mode a remote connection request can be received which will place the RPM3B into a

connected state allowing it to then start receiving data from the remote unit. The connected host

device can also send data to the RPM3B via the serial interface which will force the module to send a

connection request to the remote RPM3B module, thus effectively setting up a logical connection

between two units and allowing data to be transferred.

On receipt of a connection request from a remote unit, the RPM3B immediately enters a connected

state. This effectively allows the RPM3B modems to start sending and receiving data.

In-coming data is sent to the host via the serial port in the same form as it was given to the remote

RPM3B module.

Figure 4: RPM3B transmitting data at 28kbps during ZMODEM file transfer to a remote RPM3B