Allen-Bradley MicroLogix 1400 User Manual

Publication 1766-RM001A-EN-P - October 2008
Knowledgebase Quick Starts 643
Example
The following example configures the STI to execute sub-routine file #3
(PFN=3) every 2 seconds (SPM=2000). In the subroutine file there is an
ADD instruction simply adding the value of 1 to N7:0 each time the
sub-routine is scanned.
This example also sets the User Interrupt Enable bit and the Auto Start bit
allowing the STI to execute.
IMPORTANT:
Ladder Logic Subroutine file #3 must be created in order for
this example to work. If the subroutine is not created the CPU will fault
due to a STI Error Code 1 - Invalid File Number for PFN has been
entered.
STI:0.PFN Program File Number defines which subroutine is
executed when the SPM value has timed out. The Integer
number entered must be a valid sub-routine program file
(3…255).
STI:0/AS Auto-Start defines if the STI function will automatically
start when the MicroLogix 1400 enters run or test.
STI:0/UIE User Interrupt Enabled control bit is used to enable or
disable the STI subroutine from processing.
STI:0.SPM Setpoint (in milliseconds) defines the interval that the
interrupt will scan the PFN sub-routine.
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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