Allen-Bradley SLC 500 Series User Manual

Publication 1747-RM001G-EN-P - November 2008
2-8 Basic Instructions
Timebase
The timebase determines the duration of each timebase interval. For Fixed and
SLC 5/01 processors, the timebase is set at 0.01 second.
Timer Accuracy
Timer accuracy refers to the length of time between the moment a timer
instruction is enabled and the moment the timed interval is complete.
Inaccuracy caused by the program scan can be greater than the timer timebase.
You must also consider the time required to energize the output device.
Timing accuracy is -0.01 to 0 seconds, with a program scan of up to 2.5
seconds. The 1-second timer maintains accuracy with a program scan of up to
1.5 seconds. If your programs can exceed 1.5 or 2.5 seconds, repeat the timer
instruction rung so that the rung is scanned within these limits.
EXAMPLE
If the timer base is set to 0.01, it would take 100
counts as the preset value (PRE) to equal 1 seconds
worth of timing.

Allen-Bradley SLC 500 Series Specifications

General

Programming Software	RSLogix 500
Series	SLC 500
Category	Controller
Manufacturer	Allen-Bradley (Rockwell Automation)
I/O Capacity	Up to 4096 I/O points
Communication Ports	DH-485
Programming Languages	Ladder Logic
Operating Temperature	0 to 60 °C (32 to 140 °F)
Relative Humidity	5% to 95% (non-condensing)
Memory	4K to 64K words (depending on the processor)
Power Supply	AC or DC (depending on the module)