Subject: The difference between sink and source circuits an# 1109

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OPERATOR INTERFACE PRODUCTS

APPLICATION NOTE

Subject:  The difference between sink and source circuits

AN# 1109

Date:  April 11, 2002

Name:  Wayne Patterson

Page:  1 of 3

Description:  A description of the difference between sink and source inputs and the

difference between sink and source outputs.

Affected Products:

-

 Flex Network Modules for GLC Series

Problem:

What is the difference between sink and source inputs?  What is the difference between

sink and source outputs?

Solution:

Sink and source refer to the direction of current flow between an I/O point on an I/O

module and the connected device.  It is only relevant for DC circuits with positive and

negative polarities since current flows both directions in an AC circuit.  It is important

to select a sink or source I/O module based on the devices that you are going to

connect.  If the incorrect type module is selected, your circuit will not function properly.

Sink (N PN) inputs are most common in United States, and source (PNP) outputs are

the most common in the United States.

Check the documentation for the device that you are going to connect in order to

determine whether it is a sink or source device.

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OPERATOR INTERFACE PRODUCTS

APPLICATION NOTE

Subject:  The difference between sink and source circuits

AN# 1109

Date:  April 11, 2002

Name:  Wayne Patterson

Page:  2 of 3

Description:  A description of the difference between sink and source Inputs and the

difference between sink and source Outputs.

Sink Input

For a sink input module, the current flow is from the connected device to the input.

Source Input

For a source input module, the current flow is from the input to the connected device.

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OPERATOR INTERFACE PRODUCTS

APPLICATION NOTE

Subject:  The difference between sink and source circuits

AN# 1109

Date:  April 11, 2002

Name:  Wayne Patterson

Page:  3 of 3

Description:  A description of the difference between sink and source Inputs and the

difference between sink and source Outputs.

Sink Output

For a sink output module, the current flow is from the connected device to the output.

Source Output

For a source output module, the current flow is from the output to the connected

device.

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Document Outline

• Subject:  The difference between sink and source circuits AN# 1109
• Subject:  The difference between sink and source circuits AN# 1109
• Subject:  The difference between sink and source circuits AN# 1109