Watlow MICRODIN - Manual (Page 4)

4
Watlow MicroDIN Quick Start Guide
Communications Overview
EIA-485 Network
The MicroDIN uses the EIA-485 (formerly, “RS-485”) hardware interface to com-
municate with three wires in a half-duplex configuration, up to 32 remote
devices with a master unit on a network up to 4,000 feet long using 14-26 gauge
wire.
Modbus ™ Protocol
The MicroDIN uses Modbus ™ RTU protocol to read and write to registers that
can be viewed or changed from a personal computer. Each MicroDIN ‘parameter’
has a corresponding Modbus
™ register and access privileges. The MicroDIN para-
meter register numbers and the order of priority appear later in this chapter.
Chapter 5 details all the MicroDIN parameters, and the Appendix provides infor-
mation on how to write custom Modbus
™ applications
Set Address/Baud Rate
You must configure the communications speed and network address of the
MicroDIN controller with the eight-bit DIP switch on the top of the unit. Set the
controller address with the first six switches and the network speed (9,600 or
19,200 baud) with the eighth switch. Turn to the DIP switch page 6.
Serial Data Format
The MicroDIN uses the an 8-N-1 data format; 8 data bits, no parity, 1 stop bit,
and 1 start bit. See the data format table later in this chapter.
Wiring Tasks
In addition to wiring the controller’s input, outputs and power connections, you
must also wire the EIA-232-to-EIA-485 converter; connect your computer to the
MicroDIN, and connect the MicroDIN communications daisy chain. See
“Communications Wiring” on pages 14 and 15.
Communications Software
Watlow offers a Windows application for MicroDIN, called, WATVIEW TM which
will both set up and run multiple MicroDINs over an EIA-485 network using the
Modbus
™ protocol. For more information on WATVIEW TM, , go to www.watlow.
com/products/software.
You may also write your own application (see Appendix for more detail), or pur-
chase any of several available Modbus-capable control software packages.