DCA-DCAF wiring-programming example

This example complies with ISO13849 PLe and IEC61511 SIL 3 operation. It is an example of a relatively simple safety application where temperature sensors are represented by the two 4-wire sensors.

The example shows how to interface the field devices to a 1734-IE4S POINTGuard Analog Input module. The example illustrates how to configure the I/O modules and use I/O tags in the associated logic for this simple application, including how to use the Dual Channel Analog input instruction to control the safety aspects of this application. The standard/control part of this application is not shown.

This example does not include I/O conditioning and fault latching logic, which can be desired for diagnostic reasons.

Wiring Example

(1) Signal Return and Common are at the same potential.

(2) If the sensor has a digital output for use with the Tachometer mode, it must be a push-pull type or have appropriate pull-up or pull-down resistors for NPN or PNP type. The 1734-IE4S module does not provide low impedance of these pull-up or pull-down resistors.

(3) This wiring configuration is also used for SIL 2 redundant Tachometer mode

(4) For analog voltage output sensors, the signal levels for operation for the application must be outside the signal level when the signal is not present, for example, when the wire is broken.

Programming Example

This programming diagram shows the instructions with inputs.

Ladder Diagram

The programming software is used to configure the input parameters of the Guard I/O module, as illustrated.

Configure the module as shown in the following diagram.

Module Definition

Rockwell Automation

suggests selecting

Exact Match

for the

Electronic Keying

as shown. You can also select

Compatible Match

.

Configure the inputs of the module as shown in the following diagrams.

Module Safety Input Configuration

Module Input Configuration

Configure Module 1 Alarm Configuration for Channel 0 and 1. Configure channel 0, and then configure Channel 1 identical to Channel 0.

Alarm Configuration