Specify a discrete I/O Tag

I/O discrete tags indicate the binary state of all inputs and outputs from programmable controllers, process computers, and data from network nodes.

An I/O discrete tag must be assigned an initial value of On or Off. You can also configure the discrete I/O tag to toggle to the opposite value of its binary source. You can specify messages that appear in the alarm event window when the process associated with the tag goes into an alarm state.

For more information about the overall procedure to create a tag from the Tagname Dictionary, see Create new tags.

Define an I/O discrete tag

1. Open the Tagname Dictionary and assign a name for a new tag.

2. Assign the tag as an I/O discrete type from the Tag Types dialog box. The detail portion of the Tagname Dictionary dialog box appears.

   

3. Do the following:

   • Select On or Off as the initial value associated with the tag.

     The InTouch HMI assigns this value to the tag when the application starts, but does not write this initial value to the I/O device.

   • Select Direct or Reverse as the input conversion applied to the value received from a remote I/O tag.

     Input Conversion	Description
     Direct	The input value is read unchanged directly from the I/O Server program.
     Reverse	The I/O discrete value is toggled when read from the server program. For example, if the I/O input is 0, the value is automatically set to 1.

4. Enter messages in the On Msg and Off Msg boxes that appear when the tag transitions in and out of an alarm state.

   These messages are available for use in any animation link or script, regardless of whether the tag has alarms configured or not.

   • If you define a discrete alarm that is active when the tag value is equal to 1 (On, True), the message entered in the On Msg box appears in the Value and Limit columns of your ActiveX alarm displays.

     When the tag’s alarm state returns to normal, the message entered in the Off Msg box appears in the Value column and the On message remains in the Limit column.

   • If you define a discrete alarm that is active when the tag value is equal to 0 (Off, False), the message entered in the Off Msg box appears in the Value and Limit columns of your ActiveX alarm displays.

     When the tag’s alarm state returns to normal, the message entered in the On Msg box appears in the Value column and the Off message remains in the Limit column.

5. Save your changes to the tag.