Siemens SIMATIC 505 User Manual

Installation

Series 505 High Speed Counter 
and Encoder Module User

’s Manual

The count, inhibit, and unfiltered reset inputs are high-speed inputs which

may respond to noise present on the lines. To avoid problems, follow these
guidelines when installing the HSC module.

D Use the shortest possible wires.
D Avoid placing signal wires parallel to high-energy wires. If the two

must meet, cross them at right angles.

D Avoid bending the wire into sharp angles.
D Use wireways for wire routing.
D When using shielded wires, ground them only at the source end for

better noise immunity.

D Place wires so that they don’t interfere with existing wiring.
D Label the wires.

In some installations when both the HSC and TI505-49XX series of relay
modules are used, false counts may be induced when switching high
voltage in the relay module, (voltage > 40 Vrms). This is the result of
internal arcing of the relay contacts.

If you encounter this problem, place a snubber consisting of a 47 ohm 1/4
watt resistor and a 0.022 

Fd capacitor across the relay contact terminals

on the terminal block. Snubbers were not included in the relay modules in
order to meet the need for lower current leakage in many applications.


: Snubber components must be ULr component recognized
and/or CSA Certified for use across the rated voltage being switched
by the relay module.