Rockwell Automation D17846.2.4 CONTROLNET KT EMULA - Manual (Page 21)

Publication 1784-6.2.4 - September 1997
Chapter
3
How Your Driver Operates the KTCX Card
What This Chapter Covers To make sure that each packet of information gets to its proper
destination without error, your driver needs to know how to correctly
operate the KTCX card. So that you have the pertinent information
necessary to operate the KTCX card, this chapter describes the
following:
• General Communications Configurations
• Send and Receive Overview
• General Packet Structure
• Send Mailbox
• Receive Mailbox
• Acknowledgment Confirmation Area
General Communication
Configurations From the originating station you can communicate to any station,
such as 1770-KFCs, PLC5s, or KTCX Cards with applications that
support PCCC messaging in a ControlNet network.
Message Timeouts
The 1784-KT card did not allow for timeouts on a per message basis
but due to the nature of ControlNet, timeout conditions can vary
depending on the network parameters. To accommodate this function,
the word at offset 084h is used to set this timeout in seconds. If the
value is 0 then the timeout value is set to 120 seconds by default. Any
other value will set the timeout to that specific value. The timeout
value can range from 1 to 320 seconds. If no other node exists on the
network, the message timeout value will be substantially less.
Data Transmission and Reception
The KTCX can have a total of 15 outstanding messages. See the
example code in Appendix A for details.
Important: The KTCX uses a 186EC 20 MHz or (series A) or 25
MHz (series B) so the timings between operations will be different
when compared to the KT family of products.