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Rockwell Automation Publication 5069-UM003B-EN-P - January 2020
Chapter 3
Compact 5000 I/O Serial Module Features
Master/Slave Handshake Mode
The serial port works in a handshake mode using the following steps.
1. The serial module receives the packet.
2. If any of the following conditions occur, the serial module creates a record.
a. The Message Timeout timer expires.
b. The number of received bytes equals the configured Read Buffer Size.
c. Termination Delimiter bytes were received.
3. The record is added into the RxBuffer.
4. Once the RxID (Consume Tag) is incremented by the user logic, the serial
module takes the oldest record from RxBuffer, copies the data into the
ASCII.RxData input tag, copies the number of characters that are received
into the ASCII.RxDataLength input tag, and sends it to the controller.
Figure 8 - Serial Port Handshake Mode
Controller
RPI
Comes
RPI
Comes
Receive
Data
Produce
Data
Consume
Data
Produce
Data
Update
Switch
5069-SERIAL
RxBuffer
The Oldest Record
Decided Record
Decided Record
The Latest Record
RxFIFO
Binary
Data
Binary
Data
UART
Send
Data
Target
IMPORTANT
If Master/Slave Handshake is selected, dispose additional receiving data
from the serial port for saved data in the receiving buffer of the firmware.
