ICP DAS USA M-4132 User Manual page 69

can refer to user manual section 2.2.2. If the connection is
RS-232 and the Com Port device is a data circuit-terminating
equipment (DCE), the user just needs to match the signal
names to connect Server/Client to Com Port device, else the
user needs to use a crossover cable to connect.
Some Com Port devices will wait forever for one of the
handshaking lines to go to the correct level. Depending on the
signal state it might sometimes work, other times it might not.
Here we connect the M-4132 and the Com Port device via
handshake looped to avoid the Com Port device waits
handshake line signals, as shown in below.
M-4132 User Manual (Version 1.60, May/2014) PAGE：69