Other Caution Items - Yamaha RCX240 User Manual

3.4

Other caution items

1) The controller allows receiving data as long as the receive buffer has a free area.
The receive buffer is cleared in the following cases.
• When the power was turned off and turned back on.
• When the program was reset.
• When an ONLINE statement or OFFLINE statement was executed according to the robot
language.
• When the communication parameter was changed in "SYSTEM" mode or when initialization
was executed.
2) Turning on an external device might sent incorrect data to the robot controller which is
readying to receive data when the power is turned on. That incorrect data might then be
stored in the receive buffer if the controller is turned on prior to the external device and cause
communication errors.
In such a case,
• Reset the program before program execution.
• Clear the receive buffer by placing an ONLINE statement or OFFLINE statement at the top of
the program.
• Turn the external device on before turning the controller on.
3) When the external device does not support handshake protocols (BUSY control, XON/XOFF
control), the data processing speed becomes slower than the communication speed, causing a
communication error. In this case, take countermeasures such as reducing the communication
speed (baud rate).
4) When the communication speed is set at a high rate, communication errors might occur due
to external noise or other factors. In this case, take countermeasures such as reducing the
communication speed.
5) There is no response to external transmission during direct command execution or point trace
execution in "AUTO" mode. A response is issued after execution.
6) Improper connection to an external device might cause electrical shocks, controller
malfunctions or external device malfunctions or breakdowns, depending on the external device
type and its operating conditions.
Always comply with the following points when connecting an external device.
q When the external device has a ground wire, be sure to ground it properly.
w If using an external device that does not have a ground wire or protective ground terminal,
make sure that its structure is designed to protect from electrical shock.
3. Communication specifications
Chapter 8 RS-232C INTERFACE
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