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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 send incorrect data to the robot controller which
is ready 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.
1. When the external device has a ground wire, be sure to ground it properly.
2. 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
7
7-7
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