User manual

Computer Gateway User Manual 3-2 5/96
3.1.1
3.1.1 Advanced Control Programs (ACPs)
The preparation and installation of an ACP is a multi-step operation initiated at a host
processor terminal. In summary, those steps are
• Prepare ACP source file(s)
• Compile and link the program(s)
• Build any required Data Definition Tables
• Use the ACP Installer to install the ACP in the host processor and to make the ACIDP
connection, if CG scheduling is desired.
After the individual application program is prepared for execution in the host-processor
environment, it needs to be installed as an ACP. The installation status is recorded in the
host-processor's ACP Status Table. If there is an associated ACIDP, the ACP status is
kept there as well.
3.1.2 Data Definition Tables (DDTs)
Data Definition Tables are required to support the table-driven data transfers. They are built
at the host processor, beginning with creation of user defined source files.
Three types of Data Definition Tables are provided, Input, Output, and History. Each DDT
contains an identifier by which it is known to the ACPs, and lists of ASCII point and
parameter names. For non-History DDTs, other parameters provide for specialized
processing of data values. These include
• Apply Calculation—Specifies whether or not to perform a calculation on the data
value. A choice of 10 algorithms, some using constants and others using current data,
is offered. Applies to either Get or Store Data for Real values.
• Bad—Specifies what will happen if the value is "bad." Applies to Get Data of Real or
Integer data. Possibilities include
– Leave as is
– Substitute indicated constant
– Substitute indicated point parameter value
• High/Low Limits—The value (or result of the calculation if used) is compared against
these limits. Applies to either Get or Store Data for Real values.
• Clamp—When a limit is exceeded, specifies whether the value is clamped at its limit or
replaced by the bad value constant (-0). Applies to either Get or Store Data for Real
values.
• Test—When set and the ACIDP status is Test, the live value is replaced by a specified
value. Applies to Get Data for Real, Integer, ASCII, or Enumeration values.
• Source/Destination—Specifies an array location in the host processor where the Get
Data value is to be stored, or a Store Data value is to be taken from. Applies to Get
Data and Store Data for all value types.