Rockwell Automation Publication 5069-UM003B-EN-P - January 2020 31
Compact 5000 I/O Serial Module Features Chapter 3
Control Line Menu
When you are required to connect to a dial-up modem, see Tab l e 6  that explains 
the duplex setting in the serial port.
Generic ASCII 
Data Exchange
The following illustrations show different data exchanges using the serial module.
Data Sent with the Serial Port
Data is sent out of the serial port using the following steps:
1. The controller sends out the consumed packet with an incremented TxID.
2. The serial module puts the packet into the TxBuffer. 
3. The serial module takes the oldest data from the TxBuffer and sends it out 
to the target.
Figure 6 - Data Sent out to the Serial Port
Table 6 - Control Line Menu
Modem Duplex Status Controller Your Function Choice Continuous Carrier
Not using a modem — No Handshaking —
Using a modem Modems in a point-to-point link are full-duplex — Full-duplex
Master Modem is a full-duplex while slave 
modem is half-duplex.
Master Controller Full-duplex
— Slave Controller Half-duplex Select the continuous carrier checkbox.
All modems in the system are half-duplex. — Half-duplex Clear the continuous carrier checkbox 
(default).
Consume Data
RPI Comes
Send 
Data
Controller
5069-SERIAL
TxBuffer
TxID
Update
TxID
Non-Update
Ignore 
Data
The Latest Data
Transmit Data
Transmit Data
The Oldest Data
Binary 
Data
TxFIFO
Binary 
Data
UART
Receive 
Data
Targ et