Rockwell Automation 20-COMM-ER 20-COMM-ER Dual-Port EtherNet/IP Communication Adapter User Manual - Manual (Page 125)

Rockwell Automation Publication 20COMM-UM015B-EN-P - July 2013 125
Using Explicit Messaging Chapter 6
• 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 133 ).
• 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 and 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 133 ). 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 .
MicroLogix 1100/1400 Controller Explicit Messaging Using the
Read/Write Parameter Service
MicroLogix 1100/1400 Controller Example Ladder Logic Program to Read a
Single Parameter
A Read Parameter message is used to read a single parameter. This read message
example reads the value of parameter 003 - [Output Current] in a PowerFlex 7-
Class drive.
Figure 53 - Example Ladder Logic to Read a Single Parameter