Watlow Series 988 Family - Manual (Page 17)

3.1 Communications Setup, Chapter 3 Data Communications with the Watlow Series 988 Family
Setup
Chapter 3 Communications Setup
Connecting the Controller and the Computer
Remove power from both the controller and your computer before connecting them
together. Assemble a cable and the appropriate wiring at your computer. Refer to
the wiring in Chapter 2. As soon as you connect the data communications lines,
you may apply power to your system.
Software Protocols and Device Addresses
There are three communications protocols you may use. Depending on the type of
network you need, you must use the correct combination of interface and protocol.
Modbus works with all three interfaces.
To run a network with multiple devices Watlow uses the ANSI X3.28 Protocol
(based on ANSI X3.28 - 1976 Subcategories 2.2, and A.3) with the EIA-422 and
EIA-485 interface. ANSI X3.28 Protocol provides a response to every message. It
will also work with the EIA-232 interface, but you are limited to one controller and a
host computer.
To run a two-device network with an EIA-232 interface, you can also use XON/
XOFF Protocol, a simpler protocol. XON/XOFF will also work with the EIA-422 and
EIA-485 interface, but the network is limited to two devices — one computer
and one controller. XON/XOFF Protocol does not require a device to respond to
messages it receives.
To select the protocol, go to the Setup Menu [`SEt] ; use the up-arrow or down-
arrow key to advance to the Communications Menu [COM] . Press the MODE key
until the protocol prompt [Prot] appears. Select either [FULL] , for ANSI X3.28 2.2
- A.3, [``On] for XON/XOFF, or [Mod] , for Modbus RTU.
If you are using ANSI X3.28 Protocol, choose an address number for each control-
ler using the address prompt
[Addr] , which follows the protocol prompt [Prot] .
This prompt will only appear if [Prot] is set to [FULL] or [Mod] .
Communications Software
Watlow offers a Windows based configuration and monitoring software package for
the 988/989 controllers. We also offer a simple MS-DOS™ communications
demonstration program for the Series 981-984, 986-989, and 996-999. Ask your
Watlow field sales representative for a copy of the "Comm 4" program, or you can
download the files ("comms4.zip" and "comms4tm.zip" and com5set.exe) from the
Watlow BBS, (507) 454-3958.