User`s manual

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MELSOFT
7. SYSTEM CHECKING FROM PERIPHERAL DEVICE
• If you set the personal computer interfaces to the same COM port in GX
Configurator-QP and GX Developer, set the baudrate to the same speed.
If they are started at the same time, the baudrate set first has priority and the
baudrate set later is ignored.
• If GX Configurator-QP is forced to end in the test mode, a time-out occurs due to
the elapse of the wait time and the QD75/LD75/LD77 cancels the test mode.
• A communications error may occur if communications are made with the
QCPU/LCPU after setting of any of the resume function, suspend setting, power-
saving function and standby mode of the peripheral device. For this reason, do not
set the above functions when communicating with the QD75/LD75/LD77.
• If the USB cable is disconnected/connected, the QCPU/LCPU is reset, or power is
switched on/off frequently during communications with the QCPU/LCPU, a
communications error may occur and the system may not recover from the error.
Hence, place the system offline when disconnecting/connecting the USB cable,
resetting the QCPU/LCPU, or switching power on/off.
If the system does not recover from the communications error, completely
disconnect the USB cable once and reconnect it after more than 5 seconds has
elapsed. (An error may occur at the initial communications after this operation, but
the system will function properly from the second time onwards.)
• A communication error may occur depending on the combination of the personal
computer model, USB cable and so on.
In that case, refer to the message displayed and perform operation again.
• If the baudrate is changed at the serial port of the personal computer (personal
computer interface) to perform fast communication, communications may not be
made or a communications delay may occur due to a communications retry
depending on the performance of the personal computer.
If communications cannot be made for fast communication, reduce the baudrate
and restart communication.
• If "Multiple PLC specification" is set for the "PLC No. 2", "PLC No. 3" or "PLC No.
4" in the PLC side setting, that setting is made valid only when the QD75 of
function version "B" or later is used. To confirm the function version of the QD75,
refer to "Section 7.3 Checking the Positioning Module Function Version (OS
Information) ".