National Instruments 653X Manuale Utente

© National Instruments Corporation

Figure 2-3.  Connecting Signals

If you are using the burst protocol, make the connection to the appropriate 
PCLK pin on the 653X device.

To avoid invalid or missing data when the ACK and REQ lines change 
polarity to either active-high or active-low, start a transfer using one of the 
following methods:

•

Control the configuration and use an initialization order.

•

Select compatible line polarities and default line levels.

This startup sequence ensures the 653X  device is configured and is driving 
a valid ACK value before you enable the transfer on the peripheral device. 
Similarly, you can make sure the peripheral device is configured and is 
driving a valid REQ value before you enable the transfer on the 
653X device:

1.

Configure the 653X device for a mode compatible with your peripheral 
device.

2.

Configure and reset the peripheral device, if appropriate.

3.

Enable the input device (653X device or peripheral device) and begin 
a transfer.

4.

Enable the output device (653X device or peripheral device) and begin 
a transfer.

To control this initialization order, you need to enable and disable the 
peripheral device and control the order in which the 653X device and the 
peripheral device are enabled. You can use the extra input and output lines 
for this purpose.

ACK

REQ

I/O

Confirm

Ready

I/O

653

X

 Device

Your Peripheral Device