Basic Procedure; Instruction Terminology - Omron SYSMAC C2000H Operation Manual

Instruction Terminology

4-1

Basic Procedure

1, 2, 3... 1.
4-2

Instruction Terminology

42
There are several basic steps involved in writing a program. Sheets that can
be copied to aid in programming are provided in Appendix F I/O Assignment
Sheets and Appendix G Program Coding Sheet.
Obtain a list of all I/O devices and the I/O points that have been as-
signed to them and prepare a table that shows the I/O bit allocated to
each I/O device.
2. If the PC has any Units that are allocated words in data areas other than
the IR area or are allocated IR words in which the function of each bit is
specified by the Unit, prepare similar tables to show what words are
used for which Units and what function is served by each bit within the
words. These Units include Special I/O Units and Link Units.
3. Determine what words are available for work bits and prepare a table in
which you can allocate these as you use them.
4. Also prepare tables of TC numbers and jump numbers so that you can
allocate these as you use them. Remember, the function of a TC num-
ber can be defined only once within the program; jump numbers 01
through 99 can be used only once each. (TC number are described in
5-11 Timer and Counter Instructions; jump numbers are described later
in this section.)
5. Draw the ladder diagram.
6. Input the program into the CPU. When using the Programming Console,
this will involve converting the program to mnemonic form.
7. Check the program for syntax errors and correct these.
8. Execute the program to check for execution errors and correct these.
9. After the entire Control System has been installed and is ready for use,
execute the program and fine tune it if required.
The basics of ladder-diagram programming and conversion to mnemonic
code are described in 4-3 Basic Ladder Diagrams. Preparing for and input-
ting the program via the Programming Console are described in 4-4 The Pro-
gramming Console through 4-6 Inputting, Modifying, and Checking the Pro-
gram. The rest of Section 4 covers more advanced programming, program-
ming precautions, and program execution. All special application instructions
are covered in Section 5 Instruction Set. Debugging is described in Section 7
Debugging and Execution. Section 8 Troubleshooting also provides informa-
tion required for debugging.
There are basically two types of instructions used in ladder-diagram pro-
gramming: instructions that correspond to the conditions on the ladder dia-
gram and are used in instruction form only when converting a program to
mnemonic code and instructions that are used on the right side of the ladder
diagram and are executed according to the conditions on the instruction lines
leading to them.
Most instructions have at least one or more operands associated with them.
Operands indicate or provide the data on which an instruction is to be per-
formed. These are sometimes input as the actual numeric values, but are
usually the addresses of data area words or bits that contain the data to be
used. For instance, a MOVE instruction that has IR 000 designated as the
source operand will move the contents of IR 000 to some other location. The
other location is also designated as an operand. A bit whose address is des-
ignated as an operand is called an operand bit; a word whose address is
designated as an operand is called an operand word. If the actual value is
entered as a constant, it is preceded by # to indicate that it is not an address.
Section 4-2