Galil DMC-4040, Руководство пользователя

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Instructions are sent in ASCII, and the DMC-40x0 decodes each ASCII character (one byte) one at a time. It takes
approximately 0.05 msec for the controller to decode each command.
After the instruction is decoded, the DMC-40x0 returns a response to the port from which the command was
generated. If the instruction was valid, the controller returns a colon (:) or a question mark (?) if the instruction was
not valid. For example, the controller will respond to commands which are sent via the main RS-232 port back
through the RS-232 port, and to commands which are sent via the Ethernet port back through the Ethernet port.
For instructions that return data, such as Tell Position (TP), the DMC-40x0 will return the data followed by a
carriage return, line feed and : .
It is good practice to check for : after each command is sent to prevent errors. An echo function is provided to
enable associating the DMC-40x0 response with the data sent. The echo is enabled by sending the command EO 1
to the controller.
Unsolicited Messages Generated by Controller
When the controller is executing a program, it may generate responses which will be sent via the main RS-232 port
or Ethernet ports. This response could be generated as a result of messages using the MG command OR as a result
of a command error. These responses are known as unsolicited messages since they are not generated as the direct
response to a command.
Messages can be directed to a specific port using the specific Port arguments – see the MG and CF commands in the
Command Reference. If the port is not explicitly given or the default is not changed with the CF command,
unsolicited messages will be sent to the default port. The default port is the main serial port.
The controller has a special command, CW, which can affect the format of unsolicited messages. This command is
used by Galil Software to differentiate response from the command line and unsolicited messages. The command,
CW1 causes the controller to set the high bit of ASCII characters to 1 of all unsolicited characters. This may cause
characters to appear garbled to some terminals. This function can be disabled by issuing the command, CW2. For
more information, see the CW command in the Command Reference.
When handshaking is used (hardware and/or software handshaking) characters which are generated by the controller
are placed in a FIFO buffer before they are sent out of the controller. The size of the RS-232 buffer is 512 bytes.
When this buffer becomes full, the controller must either stop executing commands or ignore additional characters
generated for output. The command CW,1 causes the controller to ignore all output from the controller while the
FIFO is full. The command, CW ,0 causes the controller to stop executing new commands until more room is made
available in the FIFO. This command can be very useful when hardware handshaking is being used and the
communication line between controller and terminal will be disconnected. In this case, characters will continue to
build up in the controller until the FIFO is full. For more information, see the CW command in the Command
Reference.
DMC-40x0 User Manual Chapter 4 Software Tools and Communication
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