Electro Cam PL-1746 Series - Manual (Page 7)

1-2 Introduction
Introduction to Programmable Limit Switches
Resolvers & Encoders The PL-1746 Programmable Limit Switch uses a resolver or encoder instead of a cam
to indicate machine position. A resolver uses fixed and rotating coils of wire to generate
an electronic signal that represents shaft position. The resolver or encoder is usually
coupled to a machine shaft at a 1:1 ratio so that one resolver or encoder shaft rotation
corresponds to one machine cycle. Resolvers have no brushes, contacts, or any fric-
tional moving parts to wear out.
Based on the resolver or encoder signal, the PL-1746 Programmable Limit Switch turns
electrical circuits, or “Outputs,” on and off, simulating the mechanical roller limit switch.
Because the PL-1746 combined with the resolver or encoder system is completely
electronic and has no frictional parts, it offers several advantages over mechanical cam
switches:
• Long service life with no parts to wear out.
• “On” and “off” points can be adjusted instantly from the keypad; there are no cams to
rotate or replace.
• Adjustment is possible with the machine running or stopped.
• Programmable logic allows complex switching functions that are impossible with
mechanical cams.
• Operation at speeds up to 3000 RPM.
PL-1746-C01 Module Description
The PL-1746-C01 PLS (Programmable Limit Switch) Module is designed to plug into
an Allen-Bradley SLC™ 500 Series PLC (Programmable Logic Controller) chassis.
An absolute position signal is generated by a resolver connected to the module. Output
status, position, and speed information is provided to the user through the backplane of
the SLC™ 500 chassis. In addition, real world high speed power outputs and inputs
can be provided by utilizing an external PS-4108 I/O rack.
The PL-1746-C01 can be programmed either through the backplane or through a stan-
dard PS-6400 keypad/display, which plugs into the front of the module. The module
has a total of 32 outputs, which are capable of driving real world devices at high speed
via PS-4108 I/O racks. All 32 outputs are accessible through the backplane.
The PLS module will display either position or rpm, depending on speed, via a 4-digit
LED display.
The PL-1746-C01 will support:
- 32 outputs total. All outputs to be accessible through the backplane. All 32 outputs
will be available on PS-4100-13-L16 I/O racks for high speed, real world outputs.
- 8 inputs consisting of 6 group inputs, 1 First Cycle Enable input, and 1 Output Enable
input.
- 2 analog outputs, which are only available on the PS-4108 I/O rack where slimline
analog output modules can be plugged in.
- Up to 2 remote PS-6400 keypads.
- High resolution (as a standard feature), up to 4096 (12 bits).
- Leading/Trailing edge speed compensation is standard.