Hytec Electronics Ltd.
 


Data Acquisition and Control

PCI 5200 DIGITAL OUTPUT INTERFACE WITH WATCHDOG FUNCTION

Introduction 
This card provides 24 digital outputs in the form of normally-open voltage-free contacts. In addition to the 24 outputs, there is a watchdog contact with both normally open and normally closed contacts. 

Functions

The card uses a PLX Technology PCI9052 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.

The PCI5200 output card will take data from the registers and use this to drive the solid-state switches. Two registers can be used as overwrite registers - data written as ‘1’ will turn ON the corresponding switch and ‘0’ will turn OFF the corresponding switch. Two further registers can be used as selective set registers - data written as ‘1’ will turn ON the corresponding switch and ‘0’ will have no effect. Two further registers can be used as selective clear registers - data written as ‘1’ will turn OFF the corresponding switch and ‘0’ will have no effect.

The watchdog contact will be handled by a separate register, in which writing a value between 1 and 65535 will reset the watchdog. This register will then count down at 1KHz until it reaches zero (unless reset in the interim) at which point the output contact will change state. The 1KHz rate is fixed. During this counting process, the normally open contact will be closed and the normally closed contact will be open.

Signal Levels

The output contacts are low on-resistance solid state MOS switches capable of switching 100 volts at up to 50 milliamps. The contacts are also protected against excess voltage by transient suppressors.

Initial Conditions

At Power-On, a reset circuit will ensure that all outputs are in the ‘OFF’ state. In the case of the watchdog contact, this will mean that the normally open contact will be OPEN and the normally closed contact will be CLOSED.

PCI Bus Interface

Important note: This card is a  32-bit PCI card for 5-volt signalling systems. It also requires +3.3 volt power to be present on the motherboard connectors (PCI rev 2.2).

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 5200 for the output card.

Registers

[‘R/W’ means writeable and readable; ‘WO’ means write only; ‘RO’ means read only].

The output card will have seven main functional 16-bit registers: [Other registers discussed below].

Offset              Function 
0h                Overwrite outputs 1 to 16 (Bits 1-16 1=ON 0=OFF) (R/W)
2h                Overwrite outputs 17 to 24 ( Bits 1-8 1=ON 0=OFF) (R/W)
4h                Selective set outputs 1 to 16 (Bits 1-16 1=ON 0=no change) (WO)
6h                Selective set outputs 17 to 24 (Bits 1-16 1=ON 0=no change) (WO)
8h                Selective clear outputs 1 to 16 (Bits 1-16 1=OFF 0=no change) (WO)
Ah                Selective clear outputs 17 to 24 (Bits 1-16 1=OFF 0=no change) (WO)
Ch                Watchdog reset: R/W register showing the current countdown value. 
The watchdog is reset by writing to this register (1-65535). It will countdown to zero at 1KHz. A value of zero will energise the watchdog.

  

Connections

The 5200 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.
Pin      Pair                 Function 
1          35                    Signal circuit 1
2          36                    Signal circuit 2
3          37                    Signal circuit 3
4          38                    Signal circuit 4
5          39                    Signal circuit 5
6          40                    Signal circuit 6
7          41                    Signal circuit 7
8          42                    Signal circuit 8
9          43                    Signal circuit 9
10        44                    Signal circuit 10
11        45                    Signal circuit 11
12        46                    Signal circuit 12
13        47                    Signal circuit 13
14        48                    Signal circuit 14
15        49                    Signal circuit 15
16        50                    Signal circuit 16
17        51                    Signal circuit 17
18        52                    Signal circuit 18
19        53                    Signal circuit 19
20        54                    Signal circuit 20
21        55                    Signal circuit 21
22        56                    Signal circuit 22
23        57                    Signal circuit 23
24        58                    Signal circuit 24
….
33                 67 (Com.)       Watchdog (normally open).
34 (Com.)       68                 Watchdog (normally closed). Note: 34 and 67 are connected.

Additional Registers

For test and diagnostic purposes, this card has other registers which are not normally used. These are intended for Hytec test use only:
 

PCI5200 output card:
Offset              Function
10h                  Configuration ROM, catalogue number 5200 decimal. (RO)
12h                  Xilinx version number, ‘1’ at the time of writing. (RO)
14h                  Xilinx revision number, ‘1’ at the time of writing. (RO)
12h                  Configuration checksum. Sum of four registers should be hex FFFF. (RO)

Indicators

In order to assist commissioning, the card is fitted with LED indicators as follows:

PCI5200 Output Card:

This card has three LED’s: 

A green LED to show that the watchdog is running.
A red LED to show that the watchdog has timed out.
A yellow LED which flashes to show that the card has been addressed.
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Last modified: September 24, 2008