What are the trigger types?

Triggers that initiate a decode attempt either come from a source external to the reader or are generated by a timing mechanism internal to the reader itself.

Any of the following events signal the reader to perform a decode attempt when the reader is configured to respond to an external trigger:

• Pushing the physical button on the reader

• Sending the DataMan Control Command (DMCC) trigger when connected to the reader over a serial or Ethernet connection

• Receiving a digital input signal over the trigger lines of the I/O cable

• Clicking the Trigger button in the Setup Tool

• Pressing Ctrl+T from the keyboard when the Setup Tool has the focus

You can configure the reader with any of the following trigger types in response to an external event:

• Single triggering acquires a single image and attempts to decode any symbol it might contain. This trigger mode supports a read timeout.

• Manual triggering acquires images as long as the trigger signal remains active, and stops when a symbol is found and decoded or the trigger signal ends. This trigger mode does not support a read timeout.

• Burst triggering acquires a set number of images and decodes the first symbol it detects within the group. You can configure the number of images within each burst as well as the interval between each image acquisition. This trigger mode supports a read timeout. This timeout is the amount of time that will be spent on each image in the burst, and not on the burst as a whole.

• Continuous triggering acquires images as long as the trigger signal remains active, where the reader acquires images at a specific interval and attempts to scan any symbols each successive image contains. If a symbol is decoded, the reader stops accepting the trigger signal. If no symbol is decoded, image acquisition continues as long as the trigger signal remains active. If the trigger signal ends and no symbol has been scanned and decoded, the reader returns a NoRead result.

  If you configure the reader to scan for multiple symbols, then the reader will not stop acquiring images after the first symbol has been scanned and decoded but continue to scan for symbols until the number of desired symbols have been detected or the trigger signal stops. If the trigger signal ends before the desired number of symbols have been located and decoded, the reader returns a NoRead result.

  You can control the interval between image acquisitions, and specify a delay between when the trigger signal arrives and when the reader starts image acquisition. In Continuous trigger mode, the trigger interval indirectly specifies a read timeout.

The remaining trigger types do not rely on an external event but begin acquiring images as soon as you select it:

• Presentation triggering continuously scans for a symbol and decodes it each time one is detected.

  You can specify several parameters in Presentation mode, such as whether the reader will read the same code more than once or how long the reader must wait before scanning for the next symbol.

  In presentation mode, use the Automatic Exposure settings to have the reader determine the best exposure settings for a desirable level of brightness in the image. Be aware, however, that the reader uses the initial images it acquires to determine these settings, and might miss images containing a symbol for decoding. You can switch to Manual Exposure settings and specify a precise setting for the camera exposure.

  Be aware that during a decoding attempt for any particular image, all subsequent images acquired during that time are discarded.

  This trigger mode does not support a read timeout.

• Self triggering is similar to presentation triggering in that the reader continuously scans for a symbol and decodes it each time one is detected. Unlike Presentation mode, however, a decode attempt occurs with every image and the reader disables the Automatic Exposure settings that allow the reader to automatically determine the best exposure settings for a desirable level of brightness in the image.

  You can specify several parameters in Self triggering mode, such as whether the reader will read the same code more than once or how long to wait before scanning for the next code. In Self trigger mode, the trigger interval indirectly specifies a read timeout.

NOTE: Several fixed mount readers have variants (S models, L models, etc.), and many of these only support certain trigger types. Please consult the appropriate Reference Manual to check what trigger types are supported by your variant.