RACOM RipEX 1.12.2, User Manual, Page: 90 / 189

In this mode, the incoming bytes from a COM are immediately broadcast over the Radio channel.
COM port driver does not wait for the end of a frame. When the first byte is coming from a COM,
the transmission in the Radio channel starts with the necessary frame header. If the next byte arrives
before the end of transmission of the previous one, it is glued to it and the transmission on the Radio
channel continues. If there is a gap between incoming bytes, the byte after the gap is treated as
the first byte and the process starts again from the beginning. Padding is never transmitted between
blocks of bytes.
The receiving RipEX transmits incoming bytes (block of bytes) from the Radio channel to both COM
ports immediately as they come.
When the ETH interface is used simultaneously (e.g. for remote configuration), it works as the
standard bridge described above. ETH frames have higher priority, i.e. the stream from COM is in-
terrupted by a frame from Ethernet.
Stream mode is recommended to be used for time-critical application only, when the first byte has
to be delivered as soon as possible. However there is not any data integrity control. If the Baud rate
of COM is significantly lower than the Modulation rate on the Radio channel, frames are transmitted
byte by byte. If it is higher, blocks of bytes are transmitted as frames over the Radio channel.
Note: Stream mode can not be used when there is a Repeater in the network.
Advanced parameters
• Radio ARP timeout [min]
Default = 1440 [1=Min, 3579=Max]
Each IP device refreshes its ARP records within some timeout. Because of that, the device transmits
spontaneous ARP request packets to each IP address listed in its ARP table. That may generate
unwanted collisions on Radio channel. Since Radio IP and MAC addresses are not changed during
normal network operation, ARP table refreshing may be done in a long period (1440 min. = 1 day).
The RipEX spontaneously transmits an ARP reply packet after each reboot. The ARP reply packet
transmission can be also invoked by executing Maintenance/Miscellaneous/BRC Radio MAC but-
ton.</p> <p>ARP reply packet refreshes the respective records in neighbouring units. This is neces-
sary e.g. when a RipEX unit has been replaced by a spare one with the same Radio IP address.
• TX Delay [bytes]
Default = 0 [0=0ff, 1600=Max]
Each packet is delayed before it is transmitted on Radio channel for time, which is equal to the time
needed for transmittion of the number of bytes set. This time depends on the set Modulation rate.
E.g.if you want to delay all packets for time which equals the transmission time of a UDP packet
with 150 user data bytes, you need to set 178 bytes (20B IP header, 8B UDP leader, 150B user
data).
Router
Router mode is suitable for Multipoint networks, where Multi-master applications with any combination
of polling and/or spontaneous data protocols can be used. The proprietary link-layer protocol on the
Radio channel is very sophisticated, it can transmit both unicast and broadcast frames, it has collision
avoidance capability, it uses frame acknowledgement and retransmissions and a CRC check to guar-
antee data delivery and integrity even under harsh interference conditions on the Radio channel.
RipEX works as a standard IP router with 2 independent interfaces: Radio and ETH. Each interface
has got its own MAC address, IP address and Mask.
RipEX Radio modem & Router – © RACOM s.r.o. 90
Advanced Configuration