Allen-Bradley MicroLogix 1400 User Manual

237 Publication 1766-RM001A-EN-P - October 2008
Chapter 11
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:
RHC - Read High Speed
Clock
Instruction Type: Output
Application Specific Instructions
Instruction Used To: Page
RHC Provide a high performance time-stamp for performance
diagnostics and performing calculations such as velocity.
237
RPC Copy the program checksum from processor memory or from the
memory module into the data table.
239
TDF Calculate the number of 10 µs "ticks" between any two
time-stamps captured using the RHC instruction.
240
ABS
Read High Speed Clock
Dest N9:0
RHC
Execution Time for the RHC Instruction
Controller Data Size When Rung Is:
True False
MicroLogix 1400 word 2.5910 µs 0.2150 µs
long word 3.1210 µs 0.1802 µs
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Allen-Bradley MicroLogix 1400 Specifications

General

Processor	32-bit
Expansion Modules	Up to 7 expansion I/O modules
Power Supply	24V DC or 120/240V AC
Programming Software	RSLogix 500
Communication Ports	Ethernet, RS-232/RS-485 combo port
Controller Type	Programmable Logic Controller (PLC)
Series	MicroLogix
Digital Outputs	12
Analog Inputs	6 (embedded)
Analog Outputs	2 (embedded)
High-Speed Counter	6 high-speed counters
Pulse Output	2 (embedded)
Ethernet Port	Yes