Transfer From A Controller - Omron NT4S Operation Manual

Standard Mode
4.8.3.2

Transfer from a Controller

4. Sets the Data Download Active bit in the Read coordination byte.
This bit can be used by the controller to identify an incomplete data set transfer
(communication interrupted, power failure). An incomplete transfer is, however,
repeated the next time the terminal is booted.
5. Transfers the data set to the recipe buffer defined in the controller. A separate
recipe buffer can be programmed for each recipe. The recipe buffer must be at
least one byte larger than the data set (on account of the checksum) and consist
of an even number of bytes (in other words, an extra byte must be added if
necessary).
6. Transfers the checksum. The byte-wise XOR checksum (for the complete data
set) is written to the address that follows the last byte of the data set. It provides
the controller with additional protection against errors caused by incompletely
transferred data sets.
7. Resets the Data Download Active bit in the Read coordination byte.
8. Resets the recipe and data set numbers to the variables that have been pro-
grammed in the controller for this purpose. The recipe number is set to 0 and the
data set number to 255.
The various steps in this process can be monitored by the operator with the aid of
the system variable DSDnloadState.
The name of the last data set to have been loaded in the controller is stored in the
terminal for each recipe. This name can be displayed for the active recipe with the
system variable LoadDSName. If a data set has not yet been loaded in the controll-
er for this recipe, or if the data set which was loaded in the controller has already
been deleted, a question mark appears on the display instead.
Certain applications may require that individual data set values in the controller are
modified (for example, teaching) and that the modified data set is transferred back
to the operating terminal. An option to transfer data sets from the controller to the
terminal has therefore been provided.
A data set can be transferred from the controller to the terminal in either of the
following ways:
- By writing a value to the system variable StartUpload to initiate a data set read
process for the active recipe. If the value 1 is written to the system variable, the
variables will be read individually from the addresses specified during variable
programming. If the value 2 is written to the system variable, the variables will be
read as a block from the data set buffer defined for the recipe. The number under
which the data set is to be stored in the terminal can be specified via the system
variable UploadDSNr. The default setting for this system variable is 0. If a desti-
nation data set number is not entered, the transferred data set will temporarily
be stored under the number 0 and will then have to be copied to a valid number
(1-250).
Section 4-8
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