Advantech PCL-841 Series, User Manual

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3 4 PCL-841 Series User's Manual
Register descriptions
Control Register (CR)
The Control Register is used to change the behavior of the
PCX82C200. Control bits may be set or reset by the attatched micro
controller, which uses the Control Register as a read write memory.
Command Register (CMR)
A command bit initiates an action within the transfer layer of the
PCX82C200. If a read access is performed to this address, the byte
11111111 (binary) is returned.
Status Register (SR)
The Status Register reflects the status of the PCX82C200 bus control-
ler. The Status Register appears to the microcontroller as a read-only
memory.
Interrupt Register (IR)
The Interrupt Register allows identification of an interrupt source.
When one or more of this register’s bits are set, the INT pin is activat-
ed. All bits are reset by the PCX82C200 after this register is read by
the microcontroller. This register appears to the microcontoller as a
read-only memory.
Acceptance Code Register (ACR)
The Acceptance Code Register is part of the acceptance filter of the
PCX82C200. This register can be accessed (read write) if the Reset
Request bit is set HIGH (present). When a message which passes the
acceptance test is received and if there is an empty Receive Buffer,
then the respective Descriptor and Data Field are sequentially stored
in ~1:} this empty buffer. In the case that there is no empty Receive
Buffer, the Data Overrun bit is set HIGH (overrun).