Allen-Bradley 1756-DHRIO - Page 12

Publication 1756-UM514B-EN-P - February 2003
Table of Contents vi
Chapter 12
Troubleshooting the 1756-DHRIO
Module
What This Chapter Contains . . . . . . . . . . . . . . . . . . . . . . . 12-1
Checking Power Supply and Module Status . . . . . . . . . . . . 12-1
Interpreting the Alphanumeric Indicators . . . . . . . . . . . . . . 12-2
Interpreting the Status Indicators . . . . . . . . . . . . . . . . . . . . 12-3
Minimizing False Received Frame with Bad CRC Messages . 12-4
Chapter Summary and What’s Next . . . . . . . . . . . . . . . . . . 12-4
Appendix A
Specifications
Appendix B
PCCC Commands Supported by the
Data Highway Plus Module
What This Appendix Contains . . . . . . . . . . . . . . . . . . . . . . B-1
Echo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1
ID Host and Status. . . . . . . . . . . . . . . . . . . . . . . . . . . . B-2
Read DH+ Diagnostic Counters . . . . . . . . . . . . . . . . . . B-4
Reset DH+ Diagnostic Counters . . . . . . . . . . . . . . . . . . B-5
Appendix C
Application Guidelines and Tips Cached and Uncached Connections . . . . . . . . . . . . . . . . . . C-1
Cached Connections . . . . . . . . . . . . . . . . . . . . . . . . . . C-2
Uncached Connections. . . . . . . . . . . . . . . . . . . . . . . . . C-2
ControlLogix Controller Constraints . . . . . . . . . . . . . . . . . . C-2
Message Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-3
Messages Between a ControlLogix Controller
and PLC Devices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-3
RPI Configuration Settings . . . . . . . . . . . . . . . . . . . . . . . . . C-3
RPI Formula without Block Transfer Modules. . . . . . . . . . . C-4
Digital Modules Only . . . . . . . . . . . . . . . . . . . . . . . . . . C-4
Worst Case Scenario. . . . . . . . . . . . . . . . . . . . . . . . . . . C-4
Increasing the Unconnected Message Buffer Limit . . . . . . . C-4
Increasing Unconnected Message Buffer Set-Up . . . . . . C-5
Increasing Unconnected Message Buffer Source Data . . C-5
Remote I/O Performance: ControlLogix vs. PLC-5. . . . . . . . C-6
DH+ Baud Rate Comparison . . . . . . . . . . . . . . . . . . . . . . . C-7
Using Cached Connections. . . . . . . . . . . . . . . . . . . . . . C-7
Using Uncached Connections . . . . . . . . . . . . . . . . . . . . C-8
Maintaining PCCC Message Sequences . . . . . . . . . . . . . . . . C-8
Index