Programming When Data Is Received; How Timings And Flags (Contacts) Work - Panasonic FP2 User Manual

Communication with External Devices
4.3

Programming When Data is Received

4.3 Programming When Data is Received
4.3.1

How Timings and Flags (Contacts) Work

How communication is controlled
With the serial data unit, control based on the contact on and off signals is the most
secure way of carrying out data sending and reception, regardless of the position of the
slot in which the unit has been installed.
Communication is carried out using two contacts when data is sent and two contacts
when it is received, for each port.
Time chart when data is received
Received data of
RS232C port
Shared memory of
serial data unit
Executed by
serial data unit
Reception com-
pleted flag (X1)
Data register of
CPU unit
Executed by
CPU unit
Received buffer
cleared (Y11)
1. Data is received.
Operation
steps
2. Reception completed flag goes on.
3. Data is read from shared memory.
4. Received buffer is cleared.
5. Reception completed flag goes off.
6. Received buffer clear contact goes off
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FP2 Serial Data Unit