Delta RMC151 - Manual (Page 484)

RMC70/150 and RMCTools User Manual
least one switch or router connected to the network supports IGMP Query. Notice
that some switches are now available that provide both IGMP Snooping and IGMP
Query in the same switch.
6.8.10.6.8. Using EtherNet/IP Explicit Messaging
EtherNet/IP explicit messaging allows the originator (PLC or HMI) to request individual
services from the target device (RMC). These requests are made explicitly rather than being
scheduled cyclically like I/O. Explicit messaging is much more flexible than I/O in terms of
what data or services are accessed in the target device, since I/O connections must pre-
configure the I/O data to be exchanged.
In most cases, RMC users use EtherNet/IP explicit messaging to read and write registers in the
RMC. The RMC provides two methods for doing so. Also, some advanced EtherNet/IP users
may want to access standard CIP services and attributes. The following sections describe how
to use EtherNet/IP explicit messaging in each of these cases.
Reading and Writing RMC Registers using the Allen-Bradley PCCC/DF1
Services
When using an Allen-Bradley PLC with EtherNet/IP, the PLC’s MSG (message) block is
used to read and write registers in the RMC. See Using Allen-Bradley Controllers via
Message Block for details. Requests made using this method use Allen-Bradley file
addressing, which is described in the DF1 Addressing topic.
Other PLCs or HMIs that can read or write from Allen-Bradley file addresses (e.g. F7:0,
L8:16) may also be able to use this method. The underlying object in the RMC is the
Allen-Bradley PCCC/DF1 Object. This object provides services that encapsulate the
PCCC/DF1 commands and functions. The RMC implements the following PCCC function
codes:
• Diagnostic Status (06 03)
• Echo (06 00)
• SLC Protected Typed Logical Read with 2 Address Fields (0F A1)
• SLC Protected Typed Logical Read with 3 Address Fields (0F A2)
• SLC Protected Typed Logical Write with 2 Address Fields (0F A9)
• SLC Protected Typed Logical Write with 3 Address Fields (0F AA)
• PLC5 Typed Read (0F 68)
• PLC5 Typed Write (0F 67)
• PLC5 Word Range Read (0F 01)
• PLC5 Word Range Write (0F 00)
Reading and Writing RMC Registers using the Data Table Object
For PLCs that support explicit messaging, but do not support the PCCC/DF1 services
above, the RMC’s Data Table Object can be used to read and write registers. The Data
Table Object provides relatively simple services for reading and writing registers. The PLC
must build and issue a CIP Service Request and then extract the results from the CIP
Service Response. The method for issuing and receiving CIP service requests and
responses are PLC-specific.
To invoke a CIP service, you must know the object class, object instance, service ID, and
format of the request and response data. For all services in the Data Table Object, the
object class and instance will be as follows:
Field Value
Object Class 0xC0 (192)
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