Radiometrix Ltd.

VHF Narrow Band FM Radio Packet Modem

page 3

forces the RPM1 into a suspended state. Communications cannot be made with the RPM1 in this

state. WAKE/DTR pin should be pulled Low by host or connected to 0V to Enable the RPM1.

Immediately after power up and during normal operation, the RPM1 will automatically enter

standby mode where it is waiting for a connection request from a remote RPM1 module.

While in this mode a remote connection request can be received which will place the RPM1 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 RPM1 via the serial interface which will force the module to send

a connection request to the remote RPM1 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 RPM1 immediately enters a connected

state. This effectively allows the RPM1 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 RPM1 module.

Figure 4: RPM1 transmitting data at 5.3kbps during ZMODEM file transfer to a remote RPM1