CLSS Gateway - Installation and Users’ Manual | P/N:LS10248-000HW-E | REV. F | FEB/11/2022 44
Bandwidth Calculation Modbus Communications
7.5.2 IP Restrictions
The following restrictions apply:
• The CLSS Gateway must have a static IP address. Dynamic Host Configuration
Protocol (DHCP) is not supported.
• Web access via an HTTP proxy server is not supported.
7.6 Bandwidth Calculation
Use the following information to calculate the network bandwidth CLSS Gateway usage
requires and how it will impact the network.
Requirements for the Calculation
• One request and response pair requires 329 Bytes (66 + 263).
• If a client is polling at one second intervals, then request and response are both
possible in one second.
• A request and response pair creates network traffic of 329 Bytes per second (329 x 1).
• In other words, a request and response pair creates network traffic of 2632 bits per
second (329 x 8).
• Therefore, the network must be able to accommodate at least 0.0027 Mbps data flow.
• Once every five seconds, an analog request adds a small amount of network traffic.
• Formula for CLSS Gateway network bandwidth requirement based on polling rate:
Bandwidth Requirement = (329 x (1000/polling rate in milliseconds) x 8) / (10 ^ 6) Mbps
Table 7.2: Total Required Bandwidth
For TCP Request
Description Bytes
Ethernet Header 14
IP Header 20
TCP Header 20
MBAP Header 7
Message—5 bytes Function code (1) + Start Address (2) + Quantity of Registers (2) 5
Total Bytes 66
For TCP Response
Description Bytes
Ethernet Header 14
IP Header 20
TCP Header 20
MBAP Header 7
Message—Function code (1) + Byte Count (1) + Max 100 registers of each
2 Bytes (200)
202
Total Bytes 263
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