Application Specific Instructions; Rhc - Read High Speed Clock - Allen-Bradley MicroLogix 1400 Instruction Manual

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RHC - Read High Speed
Clock
ABS RHC
Read High Speed Clock
Dest N9:0
237

Application Specific Instructions

This chapter contains general information about the application specific
instructions and explains how they function in your application program.
Each of the instructions includes information on:
• what the instruction symbol looks like.
• how to use the instruction.
These instructions simplify your ladder program by allowing you to use a
single instruction or pair of instructions to perform common complex
operations.
In this chapter you will find a general overview preceding groups of
instructions. Before you learn about the instructions in each of these
groups, we suggest that you read the overview that precedes each
section. This chapter contains the following overviews:
Application Specific Instructions
Instruction Used To:
RHC Provide a high performance time-stamp for performance
diagnostics and performing calculations such as velocity.
RPC Copy the program checksum from processor memory or from the
memory module into the data table.
TDF Calculate the number of 10 µs "ticks" between any two
time-stamps captured using the RHC instruction.
Instruction Type: Output
Execution Time for the RHC Instruction
Controller Data Size
MicroLogix 1400 word
long word
When Rung Is:
True False
2.5910 µs 0.2150 µs
3.1210 µs 0.1802 µs
Publication 1766-RM001A-EN-P - October 2008
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