An ET 200M remote I/O station comprises:

• 1 or 2 (redundant) power supply modules (can be omitted in the case of a central 24 V DC supply for the plant)
• Up to 2 interface modules:
  • 1 or 2 (redundant) IM 153-2 High Feature for PROFIBUS DP connection or
  • 1 IM 153-4 PN High Feature for PROFINET connection
• Up to 12 I/O modules for connection of sensors/actuators

All I/O modules have optical electrical isolation from the backplane bus. Up to 12 I/O modules can connected to an IM 153-2 High Feature or IM 153-4 PN High Feature interface module. The IM 153-2 High Feature interface modules can also be configured redundantly.

In addition to the standard SIMATIC S7 I/O modules, special I/O modules with diagnostics capability offer the following functions, among others:

• Channel-based diagnostics, e.g. open-circuit, short-circuit, limit violations
• Internal module monitoring, e.g. configuration error, RAM error, tripped fuse
• Flatter monitoring for sensors
• Pulse stretching
• Output of a selectable substitute value on failure of the central processing unit

In the event of a fault, the modules with diagnostics capability automatically pass on the corresponding message to the operator station, permitting fast and simple troubleshooting.

The ET 200M stations can be used in standard environments and also in Ex zone 2/22. The actuators/sensors can be positioned in Ex zone 1/21 when suitable Ex input/output modules are used. Hot swapping of I/O modules within Ex zone 2 is allowed with the right permit (e.g. fire certificate).