Omron R6YXC1000, User Manual, Page: 117 / 260

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Exter
nal comm
unica
tion interf
ace
6-7
2.5 Communication flow control
Software flow control (XON/XOFF) and hardware flow control (RTS/CTS) can be set.
2.5.1 Flow control during transmit
Flow Control Description
0: None XON (11H) and XOFF (13H) do not affect transmission even when they are received. Stops transmission while CTS is OFF.
1: XON/XOFF Temporarily stops transmission when XOFF is sent from the other party. Resumes transmission when XON is sent.
2: RTS/CTS Stops transmission while CTS is OFF.
NOTE
1. Transmission stops when transmission is invalid in either of XON/XOFF or RTS/CTS flow control.
2. CTS must be on during transmission regardless of flow control When RTS/CTS is set to "None", the CTS should
always be set on. However, if CTS is connected to RTS of the other party, CTS may not always be on causing
the transmission to halt, depending on the other party specifications.
2.5.2 Flow control during receive
To prevent overflow when receiving data, XON/XOFF and RTS are used to notify the other party whether or not
it is possible to receive data.
Flow Control Description
0: None XON and XOFF are not transmitted. XON and XOFF are ignored if received. RTS is always on.
1: XON/XOFF
Transmits XOFF when available space in receive buffer falls below a certain capacity. Transmits XON when receive
buffer is empty.
2: RTS/CTS
Turns RTS off when available space in receive buffer falls below a certain capacity. Turns RTS on when receive buffer
is empty.
NOTE
"XON/XOFF" and "RTS/CTS" operate individually. For example, when all flow controls are set valid, XOFF is sent and
RTS is turned off if the free space of the receive buffer becomes insufficient. After that, when the free space of
the receive buffer is recovered, XON is sent and RTS is turned on.
2.6 Other caution items
1) The controller allows receiving data as long as the receive buffer has capacity.
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 CMU statement or OFFLINE CMU statement was executed according to the robot language.
• When the communication parameter was changed or the 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, clear
the buffer.
3) When the external device does not support the flow control, the data processing speed becomes slower
than the communication speed. 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 may occur due to external noise.
In this case, take countermeasures such as reducing the communication speed.
5) "0.5: Busy" alarm occurs if the command transmitted from the external device cannot be executed such
as during point trace execution. After the execution has been completed, retransmit the command from
the external device.
6) Electrical shock, malfunction, or breakdown of the controller or external device may occur depending on
the external device specifications and usage 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, check whether or not its structure is designed to protect
from electrical shock. Be sure to use an external device that is designed to protect from electrical shocks.