46
www.elpro.com.au
245U-E Wireless Ethernet Modem User Manual
Rev Version 2.24
Bursting
Selecting this option can increase the data throughput by reducing the
overheads associated with wireless transmissions. If communicating with a
device that does not support bursting, the modem will drop back to non-
bursting mode.
Enable Iperf Server
Enable Iperf server function in the modem. Iperf is used for performing radio
surveys or radio path testing. See “4.4 Throughput Test.”
Fixed Noise Floor
Allows the radio receiver noise floor (and therefore sensitivity) to be moved
above any interference. This essentially stops the radio from communicating
with devices that have lower signal strength. For use in areas where there is a
greater amount of interference.
Fixed Noise Floor
Due to the popularity of the 2.4 GHz band, there are many sources of interference. This interference can
sometimes be a problem due to the way 802.11 devices communicate. Standard 802.11 communications
uses a system called “clear channel assessment” which means the radio will listen before transmission
and if the channel is busy it will hold off regardless of the level of signal. If the background interference is
high due to other radio systems or noise, you can raise the fixed noise floor to compensate. The Channel
Utilization page can be used to identify excess noise or interference.
Raising the noise floor will block out any receive signal levels below the value configured under “Fixed
Noise Floor” on the Advanced Radio configuration page. The value must be entered as a negative dBm
number and should be at least 8 dB greater than the weakest RSSI of any connected modems, otherwise
communications may be lost. For example, if the interfering noise levels are around -80 dB, you can raise
the noise floor to -70 dB to block out any signals below, making sure the RSSI levels of any connected
modules are not below this noise floor as they will not communicate. The Connectivity page can be used to
determine if other systems are in the area and their RSSI levels.
After configuring the fixed noise floor, confirm that the channel utilization has dropped to a desirable level
and where possible perform an Iperf throughput test to confirm acceptable performance.
3.11 Serial Port Configuration
The 245U-E has an RS-232 and an RS-485 port for serial communications. These ports may be used for
different purposes. The 245U-E offers three serial functions—PPP server, serial gateway, and Modbus TCP to
RTU gateway.
RS-232 PPP Server
The 245U-E can be used as a PPP (Point-to-Point Protocol) server to connect the wireless system to serial
devices via the RS232 or RS485 serial ports. PPP server enables a network connection to the 245U-E over
a serial cable. This is much like dial-up Internet. The maximum serial data rate is 115,200 bps. Hardware
or software flow control may be selected. With minimal configuration on the PC, you may use dial-up
networking in Windows XP to connect to the network via the serial port.
For the 245U-E, users must configure the local IP address for the 245U-E and the remote device IP address.
Some care must be taken in selecting these IP addresses.
• If you want to use routing over this serial network connection, the IP addresses selected must not lie
on wireless or wired Ethernet networks already configured into the device. You must ensure they set
