Rockwell Automation 20-COMM-E PowerFlex EtherNet/IP Adapter - Manual (Page 155)

Using Explicit Messaging 6-29
20-COMM-E EtherNet/IP Adapter User Manual
Publication 20COMM-UM010G-EN-P
PLC-5 Controller Reading/Writing Multiple Parameters
You can read or write only contiguous parameters. Also, the range of
contiguous parameters must be contained in the same N-File. Two elements
(words) are required for each parameter being read or written. For example,
to read 5 contiguous parameters, 10 elements (words) must be used.
SLC 500 Controller
Examples
When using RSLogix 500 software, version 7.10 and earlier, explicit
messaging must be performed using the PCCC N-File method. For
RSLogix 500 software, version 7.20 and later, the CIP messaging method
has been added along with the PCCC N-File method. However, it is
recommended to use the CIP method because it is easier to use and
understand. For this reason, only instructions for the CIP method are
provided. If you must use the PCCC N-File method, see the
PLC-5
Controller Examples on page 6-23 .
The CIP messaging method provides two ways to perform explicit
messaging:
• Read/Write Parameter Service simplifies setup by requiring less data to
be entered in message configuration screens. However, the Read/Write
Parameter Service can only be used to perform single parameter read or
single parameter write explicit messages. (Multiple parameter reads or
writes must be performed using the Generic Get/Set Attribute Service
described below.)
Important: When performing a Write Parameter message, the data will
always be written to the drive’s Nonvolatile Storage (NVS).
Continuous NVS writes may damage the drive’s EEPROM.
If continuous writes are necessary, use the Generic Set
Attribute Single Service and attribute A (10 decimal; see
page 6-40 ).
• Generic Get/Set Attribute Service requires more setup data to be entered
in message configuration screens, but can be used to perform single
parameter read or write explicit messages, or multiple parameter read or
write explicit messages. Also, the Generic Set Attribute Service offers
the choice of writing the data to the drive’s Nonvolatile Storage (NVS) or
the drive’s Random Access Memory (RAM; for Generic Set Attribute
Single service only, see
page 6-40 ). Note that when selecting the data to
be written to RAM, the data will be lost if the drive loses power.
For supported classes, instances, and attributes, see Appendix C , EtherNet/
IP Objects .