Input/Output Forcing
For inputs, the force function allows one to override the actual status of external inputs by forcing individual discrete inputs to be ON or OFF. Input forces are written to the input image table and have no effect on the actual input. The value in the force table overrides the actual input. For example, if Local:0:I.Data.13 is forced to 1 (ON), it will appear in the input image and ladder logic as 1, regardless of the actual status of the device.
For outputs, the force function allows one to override the processor logic and force individual discrete outputs to be ON or OFF. Output forces are written directly to the output device and do not appear in the output image table. The value in the force table overrides the value in the output image. For example, if Local:4:O.Data.2 is forced to 1 (ON), the actual output will be ON, regardless of how it appears in the ladder and output image table.
One can program forces in one of two ways:
• Position the cursor on an instruction in the ladder program which references a real I/O address and from the right-mouse menu select Force On or Force Off.
• Edit the input or output force from the data monitor window. The force is in the “Force Mask” column. Set the force using either the tag name aliased to the physical I/O, or access the individual bit in the I/O module data tag. The current state of the force is indicated as:
(blank) there is no force for this address
1 address is forced ON
0 address is forced OFF
To change the force status of the bit, edit the entry in the “Force Mask” column.
To enable forces, locate the forces list box just below the mode selection box. Select Forces | I/O Forcing | Enable All Forces. A confirmation window will appear. Click on Yes.
To temporarily disable all forces, select Forces | I/O Forcing | Disable All Forces from the force list box. A confirmation window will appear. Click on Yes.
To remove all forces, select Forces | I/O Forcing | Remove All Forces from the force list box. You will be asked if you want to remove all forces. Click Yes to remove all forces.
For outputs, the force function allows one to override the processor logic and force individual discrete outputs to be ON or OFF. Output forces are written directly to the output device and do not appear in the output image table. The value in the force table overrides the value in the output image. For example, if Local:4:O.Data.2 is forced to 1 (ON), the actual output will be ON, regardless of how it appears in the ladder and output image table.
One can program forces in one of two ways:
• Position the cursor on an instruction in the ladder program which references a real I/O address and from the right-mouse menu select Force On or Force Off.
• Edit the input or output force from the data monitor window. The force is in the “Force Mask” column. Set the force using either the tag name aliased to the physical I/O, or access the individual bit in the I/O module data tag. The current state of the force is indicated as:
(blank) there is no force for this address
1 address is forced ON
0 address is forced OFF
To change the force status of the bit, edit the entry in the “Force Mask” column.
To enable forces, locate the forces list box just below the mode selection box. Select Forces | I/O Forcing | Enable All Forces. A confirmation window will appear. Click on Yes.
To temporarily disable all forces, select Forces | I/O Forcing | Disable All Forces from the force list box. A confirmation window will appear. Click on Yes.
To remove all forces, select Forces | I/O Forcing | Remove All Forces from the force list box. You will be asked if you want to remove all forces. Click Yes to remove all forces.
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