Block

Mask

Description

The generic Op 8255 Digital In and Op 8255 Digital Out blocks are designed to access the digital IO lines of cards featuring standard8255 Programmable Peripheral Interface (PPI) chips. The 8255 PPI features three 8-bit ports (commonly referred to as PA, PB and PC), programmable in three different modes.

The Op8255 Digital In block monitors one port of one 8255 chip and sets up the 8 lines of this port as input lines.

Parameters

8255 chip address	Enter the board address plus the offset of the 8255 chip relative to the base address of the card. (in hexadecimal format)
Port	Select one of the three available ports. 0 refers to PA, 1 to PB and 2 toPC.
Synchronize	see definition.

Inputs

This block has no inputs.

Outputs

The width of the outport must be less or equal to 8 and controls the number of channels monitored by the block. For example, if you connecta demux with 5 outports, the 5 first channels of the port will be monitored.

Characteristics and Limitations

This block can be used with boards where the 8255 chip address is directly accessible and does not require remapping or additional initialization. In later cases, a specific block must be designed.

Direct Feedthrough	No
Discrete sample time	No
XHP support	Yes
Work offline	No