Using The N:n Network - Mitsubishi Electric FX2N-485-BD User Manual

FX 485-BD COMMUNICATION BOARD
2N
8.5

Using the N:N network

1) Check the status of the RD LED and the SD LED provided on each 485 BD.
• If both of them are lighted and extinguished, nothing is wrong.
• If the RD LED is lighted/extinguished but the SD LED is not lighted/extinguished (not lighted at all), check the
setting of the station No., the transmission rate (baud rate) and the total number of slave stations.
• If the RD LED is not lighted/extinguished, check the wiring.
2) When the special auxiliary relay M8070 or M8071 is turned on, turn it off using a peripheral unit, turn off the
power of the programmable controller, then turn it on again.
3) When the RS instruction is used in the program, delete it, turn off the power of the programmable controller,
then turn it on again.
4) When the special data register D8120 for the communication format or the parameters for the communication
setting are used or when the value of the D8120 is not 0, perform the following.
• When the D8120 is used in the program, delete it, turn off the power of the programmable controller, then turn
it on again.
• Check the value of the D8120 using a peripheral unit. If it is not 0, set it to 0 using the peripheral unit, turn off
the power of the programmable controller, then turn it on again.
• When the parameters for the communication setting are used, initialize them using a peripheral unit.
5) Make sure that the sequence error (special auxiliary relays M8183 to M8190) in each slave station is not
turned on and that the special auxiliary relay M8191 is not turned off. If one of the M8183 to the M8190 is
turned on or if the M8191 is turned off, check the error code of special data registers D8211 to D8218.
Please see the following section 7.4.
DIAGNOSTICS
8
8-5