Siemens ST PCS 7 manual Electronics modules and watchdog module, 11/34, Watchdog module

© Siemens AG 2007

Process I/O

ET 200iSP distributed I/O

Electronics modules and watchdog module

■Overview ■Design

Electronics modules

The current range of electronics modules covers:

•8-channel digital input module DI NAMUR, can also be used as counter or frequency meter

•4-channel digital output module DO with external actuator switch-off via High or Low signal (H/L switch-off)

•4-channel analog input modules AI for temperature measure- ments with resistance thermometer (RTD) or thermocouple (TC)

•4-channel analog input modules AI for connection of 2/4-wire transmitters with or without HART functionality

•4-channel analog output module AO for connection of field de- vices with or without HART functionality

A TC sensor module for internal temperature compensation is provided with the 4 AI TC module, and is fitted on the corre- sponding terminals of the associated terminal module. External compensation is possible for the 4 AI RTD module by connect- ing a Pt100.

The DO modules have a switch-off function which is triggered by

11 an external signal (High or Low) from a switch-off device in the hazardous area. This permits implementation of an external switch-off independent of the automation system (controller). It is also possible to combine several DO modules into a switch-off group for this purpose. The intrinsically-safe power supply for the switch-off device is either via the watchdog module or a sep- arate intrinsically-safe source.

Watchdog module

The watchdog module has two fundamental functions:

•Monitoring of the ET 200iSP remote I/O station for hardware failures (hardware lifebeat); external, applicative failure moni- toring is also possible via an I/O address area of the module

•Intrinsically-safe power supply for external actuator switch-off

The watchdog module must be plugged onto a terminal module (order separately). The first slot directly next to the interface module is provided for the watchdog module. You can use the same terminal modules for the watchdog module as for the elec- tronics modules.

•The electronics modules are plugged as planned onto the cor- responding terminal modules using screw-type systems (TM-EM/EM60S) or spring-loaded systems (TM-EM/EM60C). The terminal modules must be ordered in addition.

•The mechanical coding of the terminal module which is car- ried out when an electronics module is plugged on for the first time prevents the connection of incorrect replacement mod- ules.

•Hot swapping of individual modules is possible under hazard- ous conditions.

•The process signals are connected to the terminals of the ter- minal modules assigned according to the plan, using either conventional screw-type or spring-loaded systems (conduc- tor cross-sections 0.14 to max. 2.5 mm²) depending on the type of module.

•All electronics modules are implemented in the EEx i "intrinsi- cally safe" degree of protection and can be easily replaced under hazardous conditions (hot swapping).

•Using a spare module plugged onto a terminal module for electronics modules (TM-EM/EM60S/ TM-EM/EM60C), you can reserve a slot for any electronics modules or close a gap resulting from the design. The spare module can be simply re- placed by the electronics module at a later point in time.

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Siemens ST PCS 7 · November 2007