PC104-PLUS1500
Functions of the board
31
The base address and the interrupt are set automatically through the BIOS.
EMC: Design in accordance with the CE regulations
8.3
Digital inputs
The board has 16 digital input channels. Two of them are interruptible. One
channel is used as counter input channel [channel 0].
The inputs acquire external signals: The input information is loaded, by the driver
functions, as numerical value into a memory cell of the system.
This numerical value calculates the status of the input signals.
All inputs have a common current ground: Digital input GND (inputs), pin 19 of
the 40-pin header.
The input current is at 3.9 mA for channels 1-15 and at 6 mA for channel 0 at
U
Nominal
. The maximal input voltage is 30 V.
Logic "1":
Input voltage at the 40-pin header is superior to 19 V.
Logisch "0":
Input voltage at the 40-pin header is inferior to 14 V.
WARNING!
If you operate all inputs with the same voltage supply,
the voltage supply
must supply the corresponding current.
The maximal input voltage is at 30 V.
Transil diodes, Z diodes, C filter and opto-couplers protect the system bus against
noise emitted by the peripheral. Thus, the effects of inductive and capacitive
noises are reduced.
For the interruptible inputs and the counter channel additional digital filters are
implemented.
The board requires no initialisation to read the 24 V digital information. After
successful Power ON Reset the data is immediately available on the board.
Fig. 8-2: Digital input level
