Serial Interface and Termination Selection
The serial interface type and input termination are selected with switch settings or through software.
Two ports use 4 positions each of an 8 position DIP switch.
The SEL0-SEL1-SEL2 switches select the interface type as shown in the image below. Valid choices are
software select, RS-232, V.35 and RS-530/422/485. Software select disables the serial interface until
configured by API call. Other selections fix the interface, preventing software modification.
The TERM switch controls the 120 ohm termination option for differential inputs (RS-530/422/485/V.11)
on a port. Single ended inputs (RS-232/V.28) never use termination regardless of the TERM switch
setting. If the serial interface is software selected then the TERM switch is ignored and termination is
enabled through software.
Interface selection is preset at the factory as specified by the ordering code.
Some interface types require a conversion cable in addition to a specific switch setting to provide the
necessary connector type. Refer to the Serial Pin Assignments section for more details.
Interface and Termination Selection
