Communication Registers; Simplified Communication Procedure - Galil Motion Control DMC-18 2 Series User Manual

Communications with the DMC-18x2
For main bi-directional communication, the DMC-18x2 features a 512 character write FIFO buffer,
and a 512 character read buffer. This permits sending commands at high speeds ahead of their actual
processing by the DMC-18x2.
Note: This chapter provides an in-depth look at how the controller communicates over the PCI bus at
the register interface level. For most users, we recommend using the drivers supplied by Galil to
provide the necessary tools for communicating with the controller.
Determining the Base Address
The base address "N" is assigned its value by the BIOS and/or Operating System. The FIFO address N
is referenced in the PCI configuration space at BAR2 (offset 18H). The following PCI information
(HEX) can be used to identify the DMC-18x2 controller:
PCI Device Identification
DEVICE ID
9050H

Communication Registers

The DMC-18x2 provides three registers used for communication. The READ register and WRITE
register occupy address N and the CONTROL register occupies address N+1 in the I/O space. The
READ register is used for receiving data from the DMC-18x2. The WRITE register is used to send
data to the DMC-18x2. The CONTROL register may be read or written to and is used for controlling
communication, flags and interrupts.
Register
READ
WRITE
CONTROL

Simplified Communication Procedure

The simplest approach for communicating with the DMC-18x2 is to check bits 5 and 6 of the
CONTROL register at address N+1.
Status Bit
5
5
6
6
Read Procedure
To receive data from the DMC-18x2, read the control register at address N+1 and check bit 5. If bit 5
is zero, the DMC-18x2 has data to be read in the READ register at address N. Bit 5 must be checked
54 ● Chapter 4 - Software Tools and Communications
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VENDOR ID SUBSYSTEM ID
10B5H 1842
Description
for receiving data
for transmitting data
for status control
Action Logic State
READ 0
READ 1
READ 0
READ 1
SUBSYSTEM VENDOR ID
1079H
Address
N
N
N+1
Meaning
Data to be read
No data to be read
Buffer not full, OK to write up to 16 characters
Buffer full. Do not send data
Read/Write
Read only
Write only
Read and Write
DMC-18x2