Related Flags And Data Registers - Mitsubishi Electric MELSEC FX Series User Manual

FX communication
9.1.3

Related Flags and Data Registers

1 ) Send request <M8122>
When M8122 is set by a pulse instruction in the receive wait status or the receive completion
status, data from D200 to D0 is sent. When send is completed, M8122 is automatically reset.
When the RS instruction drive input X010 is turned on, the programmable controller is set to
the receive wait status.
Note:
In the FX, FX
pay attention to the following points.
While the programmable controller is receiving data, send is only performed after receive is
completed. During this time, the send wait flag M8121 is actuated.
After the head data is received and before the receive completion flag M8123 is turned on, it is
regarded that a receive is being performed. If the send request is given while the head data is
received, data may be confused.
2 ) Receive completion <M8123>
• When the receive completion flag M8123 is turned ON, transfer the receive data to another
save destination, then reset M8123.
• When M8123 is reset, the programmable controller is set to the receive wait status again.
To reset M8123, use a sequence as described on the previous page.
When the RS instruction drive input X010 is turned on, the programmable controller is set to
the receive wait status.
• When an RS instruction is executed while D1 is "0", M8123 (execution completion flag) is not
actuated and the programmable controller is not set to the receive wait status. If the
programmable controller is set from this status to the receive wait status, set D1 to a value
equivalent to or greater than "1", then turn off M8123 (from the ON status).
3 ) Carrier detection <M8124>
When the CD (DCD) signal (channel receive carrier detection) is received (from the modem to
the programmable controller) when the line of the modem is established, M8124 is turned on.
While M8124 is turned off, the dial No. can be sent. While M8124 is turned on, data can be
sent and received.
, FX , FX , FX
2C 0N 1S 1N
and earlier versions than V 2.00 of the FX
RS instruction 9
and FX ,
2NC 2N
9-4