Using The No Protocol - Mitsubishi Electric FX2N-485-BD User Manual

FX 485-BD COMMUNICATION BOARD
2N
8
8.2

Using the No Protocol

1) Check the status of the RD LED and the SD LED provided on each 485BD.
• If the RD LED is not lighted when data is received, check the wiring.
• If the SD LED is not lighted when data is sent, check the confirm the connection with the programmable controller
2) When setting for the N:N network (Section 7.3.5 program) is included in the program, delete the setting, turn off the
power of the programmable controller, then turn it on again.
3) When the special auxiliary relay M8070 or M8071 is turned on, turn if off using a peripheral unit, turn off the power of the
programmable controller, then turn it on again.
4) Make sure that the communication format is equivalent between an external unit (RS232C unit) and the programmable
controller (D8120). If it is different, correct the setting of the communication parameters in the external unit or correct
the contents of the D8120 in the programmable controller. When the D8120 is corrected, restart the RS instruction.
When the communication parameters are corrected, turn off the power of the programmable controller and turn it on
again.
5) Confirm the timing of data transmission. For example, before sending the data, make sure that the counterpart
equipment is ready for receiving the data.
6) When a terminator is not used, make sure that the data quantity to be sent is consistent with the data quantity to be
received. If they are not consistent each other, let them be consistent. (If the data quantity to be sent is changed, use
a terminator.)
7) Make sure that external units are operating correctly.
8) Make sure that the send data format is equivalent to the receive data format. If they are different, let them be equivalent.
9) When two or more RS instructions are used in the program, make sure that only one RS instruction is executed in one
operation cycle.
Make sure that the RS instruction does not become OFF (unexecuted status) while data is received or sent.
DIAGNOSTICS
8-2