Galil Motion Control note 1220 Page 1
Galil Motion Control, Inc.
3750 Atherton Road
Rocklin, CA 95765 USA
Application Note #1220
Disabling handshaking with the DMC-1415/1425/1416
The hardware handshaking used on the Econo series Galil controller has changed
between the DMC-1412 generation and the DMC-1415 generation. This is not a
change that will hinder operation, but is something that must be taken into account.
The DMC-1412 architecture used the Motorola 68340, which had a 4 byte UART and
used true hardware handshaking. If the customer did not want to use the CTS/RTS
handshaking lines, the controller's processor would still handle the driving of the
appropriate lines. In this way the customer could use a three-wire setup (transmit,
receive and ground) and bypass the hardware handshaking. The only modification
necessary was to tie the controller's RTS input (Pin 4 or Pin 7) to the controller's
CTS output (Pin 1, Pin 6 or Pin 8).
The DMC-1415, DMC-1425 and DMC-1416 use the Motorola 68331 processor,
which has only a 1 byte UART. In addition, there is no true hardware handshaking
support by this processor; the handshaking is done through the controller firmware.
In this method, the PC drives the controller's RTS input line. If the standard 3-wire
setup is used to bypass handshaking, the controller may lock-up due to the RTS line
not being driven high by the PC. The simple solution to this problem is to tie the
controller RTS line (Pin 4 or Pin 7) to +12V. This +12V can be taken directly from
the ICM-1460. In this way, the controller is always in the `ready to send' state, and
can send and receive information correctly.
Because of the small buffer size of this UART, handshaking is strongly recommended
for communication between a controller and a PC. However, if the customer is using
a handheld terminal or other device where communication speed is not an issue (i.e.
9600 baud or less), this simple modification will allow proper operation of the Galil