Rockwell Automation 1747-PCINT API Software for 1746 I/O - Manual (Page 11)

Overview 1–3
Publication 1747-6.5.3 June 1998
The Windows NT API library is a DLL and must be installed on the system in order
to run an application which uses it. The Windows NT API accesses the scanner via
the driver created for the bus interface The driver:
•
allocates resources (interrupt and memory window)
•
initializes scanner hardware
•
provides access to the scanner’s dual port RAM
•
services interrupts from the scanner (priority messages)
Important: Only access the OCdriver through the API library functions.
When the OCdriver is loaded it tries to allocate an interrupt and a memory window
for the memory and interrupt that were allocated using the settings by the PCI bus
at power-up for the dual port RAM.
Understanding
the 1746 I/O PCI
Interface
Architecture
The 1746 I/O PCI Interface architecture consists of a PCI card that plugs into a PC
and cables to a 1746 I/O chassis. The scanner scans the 1746 local I/O bus and reads/
writes inputs and outputs to/from the dual port registers.
The dual port is an 8K byte memory partition (optionally battery-backed) that
provides an interface between the integrated scanner and your application software
that resides on the host.
Important: The jumper for the battery-backed dual port memory is disabled by
default. You must switch the jumper in order to enable the dual port
memory battery-backed function. By enabling the battery-backed dual
port memory, you will decrease the life of the battery.
1746 backplane interface
1747-PCIL
status and user LEDs
3-position switch
user jumper
watchdog contact
dual port memory
Partition: Bytes:
register 1K
commands variable
response variable
output image variable
input image variable
host data variable
1747-PCIS
cable
PCI bus
Scanner
CPU