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Data Acquisition and Control PCI 5221 DIGITAL INPUT INTERFACE Introduction This card is a Universal PCI card to PCI specification rev. 2.2 with 32 opto-isolated digital inputs with contact de-bounce and change-of-state detection. Functions The card uses a PLX Technology PCI9030 bridge chip to handle and decode PCI transactions. The card requests an area of I/O space into which it decodes read and write commands for on-board resources.Mode of Operation The card presents registers 16 bits wide to the PCI bus in pre-defined positions. In the case of the PCI5221 input card, reading two 16-bit registers will give the last known state of the 32 input signals. A bit in one of these registers showing a ‘1’ will denote that the corresponding input is energised. The hardware scanrate may be controlled by writing to a third register, the rate may be set from 20Hz to 250Hz, the default rate is 100Hz. The input states are further processed by being de-bounced at the sampling rate. The de-bounce works by requiring three consecutive samples of the input signal to be different from the stored state, at which point the ‘current known state’ is updated to the latest sample state for all 32 bits. Signal Levels The inputs will be protected against over-voltage and reverse voltage and will expect an operating signal of 24 volts, although they will work down to below 12 volts. PCI Bus Interface Important note: This card is a 32-bit PCI cards for 3.3 or 5-volt signalling systems. It requires +3.3 volt power to be present on the motherboard connectors. Being a Universal PCI card, it will fit in either a 5-volt 32-bit PCI slot, or a 3.3-volt 32 or 64-bit PCI slot. When the card is fitted into a PC, the BIOS will detect and assign resources as requested by the card. The resources are in the form of I/O and memory areas. One of the I/O areas is used for access to the on-board registers described above. It is the responsibility of the host software to determine the base address for this I/O area using the card’s manufacturer and model identifiers. Hytec’s manufacturer ID is 1196h and the board’s model number ID is 5221h for the input card. Registers [‘R/W’ means writeable and readable; ‘WO’ means write only; ‘RO’ means read only]. The input card will have three main functional registers. [Other registers discussed below].
Connections The 5221 card uses a 68-way SCSI-III high-density connector with signals arranged so that they run along twisted pairs in a SCSI-III cable.
The (+) and (-) indications above refer only to the input configuration where the polarity of the input voltage is relevant. Additional Registers For test and diagnostic purposes, both cards have other registers which are not normally used. These are intended for Hytec test use only: PCI5221 input card
Indicators In order to assist commissioning, the cards are fitted with LED indicators as follows:
PCI5221 Input Card: A yellow LED which flashes to show that the card has been addressed. |
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Last modified: September 24, 2008