Fairbanks FB2550 DAT SERIES DRIVER ACCESS TERMINAL - Manual (Page 94)

Section 4: Input/ Output
2/2013 94 51303 Rev. 1
5.8.4. MODBUS-TCP
MODBUS-TCP ( 30925 ) PROTOCOL was originally developed in 1978 to
exchange information between devices on the factory floor.
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It developed into the standard for exchanging data and communication
MODULE STATUS information between PLC systems.
– MODBUS-TCP devices communicate over a Serial Network in a
master/slave (request/response) type relationship.
– Uses either the ASCII (American Standard Code for Information Interchange)
mode
or the RTU (Remote Terminal Unit) mode.
 In the ASCII MODE , two eight-bit bytes of data are sent as two ASCII
characters.
– The primary advantage of ASCII mode is the flexibility of the timing sequence.
– Up to a one second interval can occur between character transmissions
without causing communication errors.
 In the RTU MODE , data is sent as two four-bit, hexadecimal characters,
providing for higher throughput than in ASCII mode for the same baud rate.
– Modbus Plus communicates using a single twisted pair of wires in one
shielded cable (#18AWG).
– Modbus Plus does NOT provide power on the network.
 Maximum of up to 32 Nodes, and up to 64 with a Repeater.
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NO. DESCRIPTION
1 Communication LED
2 Device Status LED
3 MODBUS-TCP Interface