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Setting the Transceiver Wire Mode on Ports for National Instruments Serial Boards

Primary Software: Driver Software>>NI-VISA
Primary Software Version: 3.0
Primary Software Fixed Version: N/A
Secondary Software: LabVIEW Development Systems>>LabVIEW Base Package, Driver Software>>NI-Serial, Utility Software>>Measurement & Automation Explorer
Hardware: Serial>>RS-232, Serial>>RS-485

Problem:
How can I set the transceiver wire mode for ports on my National Instruments serial boards?

Solution:
NI-VISA 3.x and later exposes the Wire Mode property through the Serial Settings properties. It is up to the user to decide how and when the Wire Mode property is set. The procedures for setting this property through Measurement & Automation Explorer (MAX) and LabVIEW are described below. Also, please refer to the Related Links section below for more information about transceiver modes for serial ports and how to set them in other ways.

The Wire Mode property can be set for a particular port in MAX before you begin programming.

1. Open MAX and expand Devices and Interfaces.
2. Expand Ports (Serial & Parallel) and click on the port whose Wire Mode property you want to change.
3. Click on the Advanced tab at the bottom of the window to the right and select the desired Wire Mode from the Transceiver Mode combo box. See the screenshot below of the Advance port settings tab in MAX.

This property can also be set programmatically in LabVIEW by using property nodes.

1. Add a property node on your block diagram and connect your VISA serial session where you want to get or set the Wire Mode property. You will need to pass the VISA resource name data lines into and out of the property node. You can also right-click on a VISA resource name line to create the property node.
2. The Wire Mode property can be found under Serial Settings when creating the property node or changing the property it is affecting.
3. Right-click to set the property node to write or read the Wire Mode property based on the needs of your application.
4. Right-click on the Wire Mode input/output to create a constant or control. See the screenshot below of the Wire Mode property node in LabVIEW and the values it can take on.

Related Links:
KnowledgeBase 3BJC7JXR: Setting Up Serial Transceiver Wire Modes Programmatically in LabWindows/CVI
KnowledgeBase 2EMAARXY: How Can I Configure My Serial Board for 2- or 4-Wire Mode in LabVIEW RT?
KnowledgeBase 17M6L0TI: What Are the Different Transceiver Modes on the NI RS-485 Serial Cards?
Developer Zone Example: Testing your 485 Serial Port in 2 Wire (Half-Duplex) Mode in LabVIEW
Product Reference: Serial Settings: Wire Mode
Product Reference: Serial Settings Properties

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Report Date: 02/10/2006
Last Updated: 09/18/2007
Document ID: 3U9E2VF3

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