====== Interoperating with Ladder Logic ======

Cubloc executes BASIC first. To enable Ladder Logic, use the command Set Ladder On.

<code xbasic>
Set Ladder On            ' If using only BASIC, don't use this statement
</code>

===== To Use Only Ladder Logic  =====

If you do not need to use BASIC, you can program in Ladder Logic alone.
But you will need a few lines of BASIC to get started, as shown below:

<code xbasic>
Const Device = CB280          ' Select device
UsePin 0,In,START             ' Declare pins to use
UsePin 1,Out,RELAY
Alias M0 = MOTORSTATE         ' Set Aliases
Alias M1 = RELAY1STATE
Set Ladder On                 ' Start Ladder.
</code>

Device model, aliases, and pin I/O mode must be set in BASIC. Ladder
Logic must be started in BASIC with the ''Set Ladder On'' statement.

===== Sharing Data ====

The Cubloc has separate BASIC and Ladder Logic data memory areas.

{{ :cubloc:works_with_ladder_logic:sharingdata.png?nolink |}}

Ladder Logic data memory can be accessed from BASIC easily by using
system variables. Using these system variables, data can be easily read
from or written to Ladder Logic data memory.

^ System Variable \\ (Array)  ^ Access Units                  ^ Ladder Logic Register                           ^
| _P                          | Bits _P(0) to _P(127)         | P Register                                      |
| _M                          | Bits _M(0) to _M(511)         | M Register                                      |
| _WP                         | Words _WP(0) to _WP(7)        | P Register (Word, ''Integer'' Access)           |
| _WM                         | Words _WM(0) to _WM(31)       | M Register (Word, ''Integer'' Access)           |
| _T                          | Words _T(0) to _T(99)         | T Register (Timer)                              |
| _C                          | Words _C(0) to _C(49)         | C Register (Counter)                            |
| _D                          | Words _D(0) to _D(99)         | D Register (Data)                               |
| _A                          | Double-Words _A(0) to _A(49)  | D Register (Floating Point, ''Single'' Access)  |
| _B                          | Double-Words _B(0) to _B(49)  | D Register (Double-Word, ''Long'' Access)       |

Registers P and M can be accessed in units of bits, and registers C, T, and D
can be accessed in units of words. 
To access P and M registers in units of
words, use ''_WP'' and ''_WD''. For example, ''_WP(0)'' represents P0 through P15.

To access the D region in units of 32-bit floating point (i.e. ''Single'') use ''_A''.  For example ''_A(0)'' represents D0 through D1.

To access the D region in units of 32-bit integers (i.e. ''Long'') use ''_B''.  For example ''_B(0)'' represents D0 through D1.

The following is an example program :

<code xbasic>
_D(0) = 1234
_D(1) = 3456
_D(2) = 100
For I = 0 TO 99
    _M(I) = 0
Next
IF _P(3) = 1 Then _M(127) = 1
</code>

Accessing BASIC variables from Ladder Logic is not possible, but you can
use [[cubloc:on_ladderint:index|Ladder interrupts]] to request a BASIC routine to change a Ladder Logic
variable.

====== How to access the D area as Floating Point ======

If the data stored in the D area is of floating point type (i.e. ''Single''), use ''_A'' instead of ''_D''.

<code xbasic>
Do
  Delay 1000
  Debug Float _A(1),Cr
Loop
</code>

The ''Single'' type is 32 bits, so it requires two D registers.

''_A(0)'' is D0 and D1.

''_A(1)'' is D2 and D3.



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