Advantech PCI-1752, Quick Start Manual

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Chapter
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frozen into its last valid value before the Channel-Freeze . Since the
value transmitted (from the host PC) to the card is also stored in the
buffers on PC, thus when user calls the
DRV_DioGet CurrentDOByte ( )
function to read back the DO channel value, this function will deter-
mine that:
If Channel-Freeze function is disabled, it will return the DO value
on the port;
If Channel-Freeze function is enabled, it will return the value from
the buffers on host PC.
The PCI-1752 provides digital input channel (CH_FRZ_IN) to enable
channel-freeze function, and PCI-1756 provides one input channel. The
channel-freeze function acts when the pin CH_FRZ_IN is activated.
Moreover, you can setup the input mode of channel-freeze function
input channel CH_FRZ_IN as dry contact input mode or wet contact
input mode selected by on-board jumper JP2, as shown in Table 4-8.
The wiring in wet contact and dry contact input mode are shown in
Figure 4-2. Otherwise, you also can enable the function through
software by writing “1” to CFC (Channel-Freeze Function Control) bit
on channel-freeze function register, as shown in Table 4-9 and Table 4-
10. It’s useful in software simulation and testing program.
The CFS (Channel-Freeze Function Status) bit shows the status of
Channel-Freeze function:
A value of 1 for the CFS bit indicates an active Channel-Freeze
Function; whereas a value of 0 indicates a non-active Channel-Freeze
Function.
Table 4-8 JP2: Channel-Freeze function input mode
PCI-1752 JP2 PCI-1756 JP2 Input mode
Dry contact input mode
Wet contact input mode(Default setting)
1
1
1
1