Rockwell Automation 2755 Enhanced Decoder Series B - Manual (Page 39)

3–9 Overview of Decoder Operations
Publication 2755-833
– Internal Timer. The trigger source is an internal timer that
cycles the trigger on and off at a set time interval
Once triggered, the decoder continuously attempts to decode bar
codes until one of the following conditions occurs:
– Number of symbols (bar codes) per package count is satisfied
– -Trigger off command (stop scan character) received from host
device (Host Decode mode)
– -Package detect signal is no longer present (Package Detect
mode)
– -No-read timer expires (Internal Timer mode)
Sending Data to Host – Speed vs. Timing
In the triggered mode, you can configure the decoder to send
information to a host device and/or operate the discrete outputs:
•
Immediately After Valid Package (for highest speed)
This is a package with valid bar code symbols that meets the
symbols (bar codes) per package count.
The Immediately After Valid Package response mode sends
decoded data to the discrete outputs and host immediately after
the decode operation. This response mode is useful in high speed
applications where maximum throughput is required.
or
•
At End of Trigger (for predictable timing)
The At End of Trigger response mode sends decoded data to the
discrete outputs and host when the:
– -Host sends the stop scan character (Host Decode mode)
– -Package detect signal expires (Package Detect mode)
– -No-read timer expires (Internal Timer mode)
This response mode is useful when timing of the discrete outputs
or timing of host communications is critical.
No-read messages are always sent at the end of the trigger.