Advantech PCI-1731 Uživatelský manuál stáhnout pdf (Strana 42)

Chapter 4

– 35 – PCI-1752/54/56 User’s Manual

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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 2 ... 37 38 39 40 41 42 43 44 45 46 47 ... 61 62

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Advantech PCI-1731 Uživatelský manuál Strana 42