Rs Instruction; Diagnostics - Mitsubishi Electric MELSEC FX Series User Manual

FX communication

12.5 RS Instruction

12.5.1

Diagnostics

1 ) Check the status of the RD (RXD) LED and the SD (TXD) LED provided on the optional
equipment.
• If the RD (RXD) LED is not lighted while data is received or the SD (TXD) LED is not lighted
while data is sent, check the installation and the wiring.
• When the RD (RXD) LED is lighted while data is received or the SD (TXD) LED is lighted
while data is sent, the installation and the wiring are correct.
2 ) Cheek the timing of data send/receive. For example, make sure that the counterpart
equipment is ready for receive before starting to send data to it.
3 ) When the terminator is not used, check whether the send data capacity is equivalent to the
acceptable data capacity. If the send data capacity may be changed, use the terminator.
4 ) Make sure that the external equipment is operating correctly.
5 ) Check whether the type of send data and the type of receive data are equivalent. If they are
different, make them equivalent.
6 ) When two or more RS instructions are used in the program, make sure that only one RS
instruction is actuated in one operation cycle.
Never turn off the RS instruction while data is received or sent.
7 ) In the FX
equipment receives "NAK".
Arrange the system so that the RS instruction is executed even if the counterpart equipment
receives "NAK".
Series (V 2.00 or later), an RS instruction is not executed if the counterpart
2N
Diagnostics 12
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