User`s manual

Watlow EZ-ZONE™ RUI/Gateway • 16 • Chapter 5 Networking with a Gateway
Using DeviceNet™
(Communications To/From a PLC):
There are two methods to communicate to/from a
PLC, i.e., implicitly and explicitly. Once the gateway
instance is enabled for DeviceNet™ there are two
prompts that relate directly to these forms of commu-
nication.
Use the graphic on the following page (RUI being
used as a DeviceNet™ Gateway) in reference to the
description below.
ost (CIP Offset) Used with explicit messages
where this prompt defines the instance off
set. The CIP offset is unique to each gateway
instance and should not overlap from one
gateway instance to another.
As an Example:
When programming the message instruction in the
PLC the class, instance, and attribute need to be de-
fined. To read the first instance of the process variable
in PM2 enter the following information in the message
instruction:
Class = 104
Instance = 5
Attribute = 1
Note that the instance is identified as instance 5 and
not 1. RUI prompt entry for gateway instance 1 fol-
lows:
[oSt] = 0
RUI prompt entry for gateway instance 2 follows:
[oSt] = 4
Likewise, to read the process value instance 2 of PM4
the following information would need to be entered in
the PLC message instruction:
Class = 104
Instance = 14
Attribute = 1
RUI prompt entry for gateway instance 3 follows:
[oSt] = 8
RUI prompt entry for gateway instance 4 follows:
[oSt] = 12
[a;nb] (CIP Assembly Size) Used with implicit mess-
ages where this prompt defines the implicit
Assembly size. For any given RUI gateway
the input and output assembly size will never
be greater than 20 members. The user entry
ranges from 0 to 20 where all members can
be dedicated to one gateway instance or they
can be distributed any way the user sees fit
across the EZ-ZONE family controllers on the
network. As indicated in the graphic on the
following page the second instance of the RUI
[CoM] menu will require that a DeviceNet™
node address be defined along with the net-
work baud rate.
Using the graphic below as an example, if:
[Gtw] instance 1 has [a;nb] set to 5
[Gtw] instance 2 has [a;nb] set to 5
[Gtw] instance 3 has [a;nb] set to 5
[Gtw] instance 4 has [a;nb] set to 5
Note that the maximum assembly size of 20 has
not been exceeded.
Each of the four EZ-ZONE family controllers will
contain the first 5 members of the assembly and this
information would then be passed implicitly to the
master on the DeviceNet™ network. Go to the Watlow
web site and download the EZ-ZONE PM Communi-
cations User Manual to find more information and
examples on the DeviceNet™ CIP assembly structure.
The EDS (Electronic Data Sheet) can be found on our
website as well. Point your browser to: http://www.wat-
low.com/literature/pti_search.cfm