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Download Main Resource ISOET84300 Hardware reference guide
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Network Configurations Quantum Modbus and Modbus Plus Communications Overview Each Quantum CPU includes both a Modbus and Modbus Plus communications port. The features offered by both these communication protocols are listed in the following table. Modbus and Modbus Plus Features The following table shows the Modbus and Modbus Plus features. Features Modbus Modbus Plus Technique Slaves polled by a master Peer-to-peer, token rotation Speed 19.2K typical 1M Electrical RS-232, various others RS-485 Distance without repeater RS-232, 50 ft. (15 m) 1,500 ft. (457 m) Media Various Twisted pair, Fiber optics Max nodes per network 247 64 Max network traffic 300 registers/sec @ 9.6 Kb 20,000 registers/sec Programming Yes Yes Read/Write data Yes Yes Global data No Yes Peer Cop No Yes Modbus Modbus, a master/slave protocol, is a de facto industry standard with support from over 500 industrial suppliers. On-line programming or data acquisition applications are easily supported directly from the serial port of any computer. Modbus can be used in either a simple point-to-point manner with a pair of devices, or in a network architecture with up to 247 slave devices. Modbus Plus Modbus Plus combines high speed, peer-to-peer communication and easy installation to simplify applications and reduce installation costs. It allows host computers, controllers and other data sources to communicate as peers throughout the network via low-cost twisted pair cable or optional fiber optic cable. 48 35013379 11/2011
