User guide

P/N: 021-00154, Rev. A.6 - updated for V4.7 Tools Page | 20
project (“projectname.dvc”) into a directory of your choosing and to reopen a previously saved project. When
your project is compiled (or make is run) five files are created for a project. These files have .dvc, .bak, .inf,
.mem and .pgm file extensions.
.dvc is the project file that contains the program text and input/output configuration data
.bak is the project backup file
.inf is the DVC70 configuration file used when downloading data from the DVC70 to the PC
.mem is the memory image describing the system inputs and outputs configurations
.pgm is the DVC5/7/10 program file in a loadable format
1.12 Input Output Configuring
The DVC5/7/10 and the DVC expansion modules are all configurable using the Programming Tool’s graphical
displays. Each module’s input and output pin’s characteristics (sensor voltage range, valve coil currents, etc.)
as well as display and logging module fields can be specified. Once the values are specified, the DVC5/7/10
BIOS will read or write to the inputs and outputs or modules as specified.
1.13 Input Output Variables and Programming
The DV
C5/7/10 execution environments allocate a memory area for each Input/Output of every module in the
system. This includes the expansion modules if they are used. The expansion modules send messages to the
DVC5/7/10 containing the values to be stored in their memory area on a periodic basis. This area is where
values
such as the input voltage, the percent of the range and error flags such as an open or short circuit has been
detected are recorded. The memory is allocated irrespective of whether or not a specific I/O is used in the
system or referenced in the application code. The memory area for each I/O is continually updated by the BIOS
and can be written to by the application code itself in some cases. Particular sections (typically a 2 byte word or
a single bit) of a I/Os memory area are identified by a variable name such as Dig_1 or Ana_1. For instance to
check if a switch has been closed you would write “If (Dig_1 = True)”. To check to see if that input has noted an
error you
would write “if (Dig_1.open = True or Dig_1.short = True) “. Each memory area has a predefined set of variable
names that are associated with specific sections (values) in the memory area.
1.14 Programming Example
The follo
wing example illustrates the general constructs used and the screen displays for configuring Inputs and
Outputs. The example is a relatively simple steering application that has been implemented using a DVC5
control module. The code consists of 4 parts namely:
Open loop test code for each I/O
The virtual display code for monitoring program execution and variables
Error checking for the status of the wiring connections in the
Always code
The unit LED updates
The actual steering control code