ProSoft Technology MVI46-GSC - Manual (Page 54)

MVI46-GSC ♦ SLC Platform Reference
Generic Serial Communication Module
Page 54 of 78 ProSoft Technology, Inc.
December 5, 2007
Write-Only Devices
Write-only devices are those that only send data to the module. An example of
this type of device is a barcode reader. The reader is programmed to only send
data and is not expected to receive data. In this configuration, the application port
on the MVI46-GSC module will never transmit data. All data received from the
device will be passed from the module to the SLC processor through the
module's M1 file. Ladder logic in the processor must handle the data received
from the module. Word 100 of the M0 file will only be used to inform the module
when the input image has been processed. This is accomplished by copying
word 0 of the M1 file to word 100 of the M0 file. The data flow diagram for a write-
only device is shown below: