Rockwell Automation 1760-xxxx Pico Controller User Manual - Manual (Page 40)

Publication 1760-UM001D-EN-P - September 2005
2-16 Installation
Wire Lengths
Severe electromagnetic interference to wires can cause inputs to signal
1 without the proper signal being applied. Observe the following
maximum cable lengths:
• I1 to I6, I9 to I12, R1 to R12: 40m (130 ft) without additional
circuits
• I7 and I8: 100m (330 ft) without additional circuits
Two-wire proximity sensors have a residual off-state leakage current.
If this residual current is too high, the input may indicate the input is
ON when the device is actually off.
Use inputs I7 and I8 for these types of input devices. If more inputs
are required, use a bleeder resistor or bleeder capacitor for inputs I1
through I6, and I9 through I12.
Increase the Input Current
Use the following input circuit for electrical noise immunity and when
using two-wire proximity switches:
When using a 100 nF capacitor, the drop-off time of the input
increases by 66.6 ms at 60 Hz (80 ms at 50 Hz). Also, a capacitor
increases the amount of current seen by the input device. Do not use
a bleeder capacitor in conjunction with reed switches.
ATTENTION
Do not use reed relay contacts on I7 or I8. These
may burn or melt due to the high current of I7 and
I8.
L1
1A
L2
L1 L2 I2 I3 I4 I5 I6 I7 I8 I1
100 to 240V ac
50/60Hz
Inputs x 100 to 240V ac
30K Ω, 5W resistor; or
100 nF, 275V ac capacitor