Siemens SIMATIC S7-1500 System Manual page 84

Pulse width modulation
PWM
Configuration:
Assignment
You can assign the inputs/outputs with frame 39x of the CPU (see also section
1)
Configuration of the digital inputs and digital inputs/outputs (X122/X132) (Page 135)).
Note
Shielded cables are required to ensure the best possible immunity of the digital inputs if they
are being used as measuring inputs.
Connection cables for digital inputs and digital outputs
Use rigid or flexible cables with a conductor cross-section as specified in the SIMATIC Drive
Controller manual for wiring the inputs/outputs.
Note
Maximum permissible cable length
The maximum permissible cable length for the connection cable is 30 m.
Overvoltage protection for signal lines
Overvoltage protection devices are required for lines of > 30 m. You are advised to use the
following snubber to protect the 24 V signal lines from overvoltage:
Table 6- 2
Line
24 V signal lines
Snubbers must always be positioned at the edge of the area to be protected, for example at
the entry to the cabinet. All 24 V lines leaving the protected area must run through a
snubber. You can find additional information on overvoltage protection in the SINAMICS
S120 manual "Booksize Power Units
(https://support.industry.siemens.com/cs/ww/en/view/109754297)".
SIMATIC Drive Controller
System Manual, 11/2019, A5E46600094-AA
6.7 Digital inputs and digital inputs/outputs X122, X132 and X142
X122, X132
DI0 to DI7, DI17, DI18,
DI20, DI21
No
Configurable channel-
by-channel on the drive
Recommendations for overvoltage protection
DI/DQ 8 to 15
No
Configurable channel-
by-channel on the drive
Overvoltage protection device
Manufacturer: Weidmüller article: MCZ OVP TAZ
Article number: 844915 0000
Connecting
X142
DI/DQ 0 to 7
Yes
Configurable channel-
by-channel on the CPU
83