Elpro Technologies 450U-E Wireless Ethernet Modem & Device Server User Manual
Rev Version 1.0.12-Beta7
www.cooperbussmann.com/wirelessresources
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Note: Modems must be ordered to operate in the chosen band; modems cannot be tuned to a
frequency that is outside of this band.
Transmit and Receive frequencies are configured by typing the frequency into the available TX and RX Frequency field.
Frequency must be multiples of the step size and will automatically adjust itself to the correct format when you click out of
the input box.
Receiver
The Radio Receive Sensitivity will vary depending on the radio channel width, whether it is a wide band radio using 25
KHz channels or if it a narrow band radio using 12.5 KHz channel. The transmit data rate will also vary the receiver
sensitivity. Refer to the table below for Receiver Sensitivity
Receiver Sensitivity
Baud Rate
Bandwidth
4.8kbits
9.6kbits
19.2kbits
25KHz Channel
N/A
-110 dBm
-99 dBm
12.5 KHz Channels
-111 dBm
-100 dBm
N/A
Radio Throughput
There are a number of throughput estimations that may help to determine the amount of data that can be successfully
transmitted through the modems. These throughput estimations are based on perfect radio conditions, i.e. little to no
outside radio interference present while data is being passed and they are calculated using real life conditions and
communication constraints.
The performance of a wireless link is best measured in terms of the maximum throughput that can be achieved. The
recommended method of measuring throughput is to use an external Modbus Client to poll the internal Modbus Server on
the remote modem. It is recommended that the throughput test be performed on point to point links while the remainder
of the wireless network is inactive (i.e. not sending any data).
Modbus TCP.
Below is a table showing the maximum number of polls per minute (ppm) based on the radio receiver signal level.
Results show two different test polls using two different data speeds and with and without Data Compression. For more
details on what data compression is and how to implement it, read section 3.10 Data Compression .
The test is designed to simulate a Modbus TCP Client polling a Modbus TCP server through the radio modems utilising
the two different data rates (2 Level FSK and 4 Level FSK) and scanning a different number of I/O points.
Setup for the Modbus Client was made to simulate the fastest polling rate possible and then determine the number of
messages that were successfully polled in a one minute period. TCP Client scan rate was 5msec, poll delay was 5msec
and the Slave response time was 10seconds.
Typical results for this setup are shown below.
Data Throughput Modbus (Polls per Minute)
4800 baud (2 level FSK)
9600 baud (4 Level FSK)
20 Words @ maximum Scan rate without compression
55 Ppm
90 Ppm
20 Words @ maximum Scan rate with Compression
58 Ppm
87 Ppm
120 Words @ maximum Scan rate without compression
39 Ppm
69 Ppm
120 Words @ maximum Scan rate with Compression
55 Ppm
87 Ppm
