Watlow Electric Gateway & DeviceNet manual Using an Allen-Bradley CompactLogix PLC

RUI/Gateway & DeviceNetTM

Configuration & Ladder Logic Example

Using an Allen-Bradley CompactLogix PLC

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).

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