Watlow Electric Gateway & DeviceNet - Manual (Page 14)

RUI/Gateway & DeviceNet TM
Configuration & Ladder Logic Example
Using an Allen-Bradley CompactLogix PLC
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© 2007 Watlow Electric Mfg Co 14
4/08
25. Notice above that there are screen shots for the configuration and communication tabs.
Within the configuration, the programmer will need to specify whether this is a read (Get) or a
write (Set) operation as well as the class, instance, and attribute (CIA) of interest. The CIA for
all PM controls is 150, 2, 8 respectively. The CIA shown above in hexadecimal represents the
Non-Volatile Save parameter for node 4 going through the RUI/Gateway (see step 24 for
explanation). The communication tab allows the programmer to select a configured I/O
module to send or receive the message where the port number and node address need to be
identified. Again, as can be seen above the module is defined in the I/O structure as
DNet_Scanner.
26. If it is desired to write a new value to the member above simply change the service type to set
attribute and define the source element with the new value.
Note:
If attempting to read or write to this parameter (Non-Volatile Save) in the EZ-ZONE
® ST the
class, instance, and attribute is different from what is shown above in step 24. For the ST, the
Class = 117, Instance = 1, Attribute = 51. The numbers shown are in decimal where the class
and the attribute will need to be converted to hexadecimal for the message instruction.
27. As another example of explicit messaging, to read a specific member such as PV1 of PM1 as
shown in the graphic above (step 17) the MSG instruction in the PLC would be configured
with the class equal to 104, instance would be 1, and the attribute would be 1 as found in the
EZ-ZONE
®
PM Communications Manual under the Operations Page. On the other end of the
network, if it were desired to read the same member from PM3, the MSG instruction would
be configured with the class equal to 104, instance would be 9, and the attribute would be 1.
Because the CIP offset is equal to 8 for gateway instance 3 the gateway will route the
message to PM3, retrieve the first instance of the Analog Input in this case PV1, and then
send it back out to the PLC.
28. As stated in step 22 the RUI/Gateway is equipped with implicit I/O assemblies. The graphics
below represent the I/O default assemblies as shipped from the factory. The T to O input
assembly (Target - Gateway) to (Originator - PLC) consists of twenty one members and the O
to T (Originator - PLC) to (Target - Gateway) consists of twenty members. Again, these
graphics represent the factory defaults for the implicit I/O assemblies. With one exception,
any of the individual members in either assembly can be user programmed. The exception
can be found as the first member of the T to O assembly “Device Status” (more on this to
follow).