Setting Up An Rs-485 Network; Picomotor Controller Rs-485 Lan Topology - Newport New Focus Picomotor 8743-CL User Manual

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Picomotor Controller RS-485 LAN Topology

Note that a multidrop bus is a computer bus in which all components are connected
to the same set of electrical wires. A process of arbitration determines which device
gets the right to be the sender of information at any point in time. The other devices
must listen for the data that is intended to be received by them. Multidrop buses have
the advantage of simplicity and extensibility.
5.5.1

Setting up an RS-485 Network

All the controllers on an RS-485 network must have unique addresses in order for a host
PC to communicate with them individually. In the case of Picomotor Controllers, these
addresses can be values (integers) between 1 and 31. Since the default address of a
controller is 1, users must change the addresses of the controllers to unique values.
There are two (2) ways—manual and automatic—in which unique addresses can be
assigned to all the controllers. The manual approach involves powering ON only one
controller at a time, connecting this controller directly to a host PC via USB/Ethernet,
changing the address to a desired value using "SA" command, saving the address in the
controller using "SM" command, and powering OFF the controller. This process must be
repeated for all the controllers on the network.
Picomotor Controllers support a novel automatic approach that allows a master controller
to assign unique addresses to all the slave controllers. The automatic approach involves
powering ON all the controllers on the network, issuing "SC" command to initiate scan
process, and waiting for the scan process to complete by monitoring the scan status via