DMC-18x2
Chapter 4 - Software Tools and Communications • 55
for every character read and should be read until it signifies empty. Reading data from the READ
register when the register is empty will result in reading an FF hex.
Write Procedure
To send data to the DMC-18x2, read the control register at address N+1 and check bit 6. If bit 6 is
zero, the DMC-18x2 FIFO buffer is not almost full and up to 16 characters may be written to the
WRITE register at address N. If bit 6 is one, the buffer is almost full and no additional data should be
sent. The size of the buffer may be changed (see "Changing Full Flags" below).
Any high-level computer language such as C, Basic, Pascal or Assembly may be used to communicate
with the DMC-18x2 as long as the READ/WRITE procedure is followed as described above. Example
software drivers are contained on the COM-DISK from Galil.
Advanced Communication Techniques
Changing Full Flags
The Full flag (Bit 6 of the control register) can be configured to change states at a different level from
the default level of 16 characters.
The level, m, can be changed from 16 up to 256 in multiples of 16 as follows:
1. Write a 5 to the control register at address N+1.
2. Write the number m-16 to the control register where m is the desired Almost Full level
between 16 and 256.
For example, to extend the Almost Full level to 256 bytes, write a 5 to address N+1. Then write a 240
to address N+1.
Clearing FIFO Buffer
The FIFO buffer may be cleared by writing the following sequence:
Read N+1 address
Send 01H to N+1 address
Send 80H to N+1 address
Send 01H to N+1 address
Send 80H to N+1 address
Read N+1 address
(Bit 7 will be 1)
It is a good idea to clear any control data before attempting this procedure. Send a no-op instruction,
by reading N+1 address, before you start. All data, including data from the DMC-18x2, will then be
cleared.
Clearing the FIFO is useful for emergency resets or Abort. For example, to Reset the controller, clear
the FIFO, then send the RS command.
Data Record
DATA TYPE
ITEM
BLOCK
UB 1
st
byte of header
Header
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Summary of Contents for DMC-18 2 Series
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