Advantech PCI-1625U User Manual

Each Com Port tab represents a specific port you have selected for test 
and configuration. On the tab, you can see the Transfer Mode, Port Sta-
tus, and Message Logo area.

Transfer Modes
You can specify the transfer mode to be Normal, loopback (active) or 
loopback (passive).

Normal—allows data to be transmitted and received simultaneously. The 
data reception rate is helpful in identifying the performance of a commu-
nication card installed on your system.

Loopback- In loopback mode a series of special data will be transmitted, 
which are expected to appear on the receiving end. Using the loopback 
mode, you can check the integrity of received data and find whether any 
error occurred on the transmission line. The active loopback and passive 
loopback must work in pair to enable the loopback mode. When a port 
operates as active loopback mode, it will send data first and receive data 
later. Another port, which operates as passive loopback, will retransmit 
any received data on the Rx line and then send these data onto the Tx line. 
These two modes will form a logical loop and help to verify the integrity 
of data transmitted over the communication link.