Rockwell Automation 1755-OF8 GuardPLC Controller Systems - Manual (Page 52)

52 Publication 1753-UM001C-EN-P - March 2010
Chapter 4 Wire GuardPLC 1600, GuardPLC 1800, and GuardPLC 1200 Controllers
High-speed Counters The GuardPLC 1200 and 1800 controllers feature inputs for high-speed
counting up to a maximum of 100 kHz. These counters are 24-bit, and
are configurable for either 5V or 24V DC. The counters can be used as
a counter or as a decoder for 3-bit Gray Code inputs. As a counter,
input A is the counter input, input B is the counter direction input,
and input Z is used for a reset.
The counter inputs must be connected by using shielded, twisted-pair
cables for each measurement input. The shields must be connected at
both ends. The input lines should be no more than 500 m (1640 ft) in
length. All reference (L-, C-, or I- depending on the controller)
connections are interconnected on the module in the form of common
reference pole.
Cables are clipped to the shield contact plate when connecting
counter inputs. See the instructions for connecting shielded cabling to
the shield contact plate on page
48 .
IMPORTANT
D
Do not terminate unused high-speed counter inputs.