PACSystems™ RX3i and RSTi-EP CPU Reference Manual Section 6
GFK-2222AK October 2019
Serial I/O, SNP & RTU Protocols 147
6.2.7.1 Retrieving Data from the Buffer
Data can be retrieved from the buffer using the Read String or Read Bytes function. It is
not directly accessible from the application program.
If data is not retrieved from the buffer in a timely fashion, some characters may be lost.
6.2.7.2 Example Command Block for the Set Up Input Buffer
Function
Status word memory type (%R)
Status word address minus 1 (%R0001)
Setup input buffer command
6.2.8 Flush Input Buffer Function (4302)
This operation empties the input buffer of any characters received through the serial port
but not yet retrieved using a read command. All such characters are lost.
6.2.8.1 Example Command Block for the Flush Input Buffer Function
Status word memory type (%R)
Status word address minus 1 (%R0001)
Flush input buffer command
6.2.9 Read Port Status Function (4303)
This function returns the current status of the port. The following events can be detected:
1. A read request was initiated previously and the required number of characters has
now been received or the specified time-out has elapsed.
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