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page 439

• To cause an interrupt when a bit changes the following bits can be set. S:46 - the program file to run when the input bit changes

S:47 - the rack and group number (eg. if in the main rack it is 000) S:48 - mask for the input address (eg. 0000000000000100 watches 02) S:49 - for positive edge triggered =1 for negative edge triggered = 0

S:50 - the number of counts before the interrupt occurs 1 = always up to 32767

24.2.9 Block Transfer Functions

Certain PLC cards only have a single address (eg. O:001 or I:001) but multiple data values need to be read or written to it. To do this the block transfer functions are used.

These will be used in the labs for analog input/output cards.

These functions will take more than a single scan, and so once activated they will require a delay until they finish.

To use the write functions we set up a block of memory, the function shows this starting at N9:0, and it is 10 words long (this is determined by the special purpose card). The block transfer function also needs a control block of memory, this is BT10:1

 

 

 

 

 

 

 

BT10:1/EN

Advance

Block Transfer Write

 

 

 

 

 

 

Module Type Example Output Card

 

 

 

 

 

 

 

 

 

 

 

 

Rack 00

 

 

 

 

 

 

Group 3

 

 

 

 

 

 

Module 0

 

 

 

 

 

 

Control Block BT10:1

 

 

 

 

 

 

Data File N9:0

 

 

 

 

 

 

Length 10

 

 

 

 

 

 

Continuous No

 

 

 

 

 

 

 

 

 

 

 

 

 

 

• To read values we use a similar method. In the example below 9 values will be read from the card and be placed in memory locations from N9:4 to N9:11.

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