Siemens SIMATIC S7-1500 System Manual page 66

Wiring
5.8 Front connector for the I/O modules
Properties of the front connectors
The three different front connectors are characterized as follows:
● 40 clamping points each
● Connection technology: Screw terminal (for 35 mm modules only) or push-in terminal
● Module width: 35 mm or 25 mm
● If you want to supply load groups with the same potential (non-isolated), use the potential
bridges supplied to the front connectors for the digital I/O modules. In four locations:
9 and 29, 10 and 30, 19 and 39, 20 and 40, the terminals can be bridged by means of
potential bridges. Advantage: Reduction of the wiring effort.
Note
Use of potential bridges
The use of potential bridges depends on the relevant module used.
Potential bridges may not be used for 230 V modules. Use the potential bridges only with
a maximum supply voltage of 24 V DC. The current capacity per potential bridge is 8 A
maximum.
Owing to the different assignment for analog I/O modules, potential bridges may not be
used
The front connectors for 25 mm modules have no potential bridges.
Observe the instructions and wiring rules in the product manual of the respective I/O
module when using potential bridges.
● In the delivery state a coding element is located in the module. When the front connector
is first inserted into the I/O module, a part of the coding element clips onto the front
connector. When the front connector is removed from the I/O module, one part of the
coding element remains in the front connector, and the other part remains in the I/O
module. The insertion of a front connector that is not suited to the module is thereby
mechanically prevented. This ensures, for example, that the front connector with the
coding element of a digital module cannot be inserted into an analog module.
Reference
Additional information about the coding element is available in the section Coding element at
the I/O module and at the front connector (Page 184).
Further information on the use of the potential bridges can be found in the product manual
for the respective I/O module.
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Automation system
System Manual, 12/2014, A5E03461182-AC