2.3.4
TTL Control
(USB-1SP16T-83H only)
2.3.4.1
Set up instructions
•
Connect the control lines (5 bits) to a suitable I/O controller.
•
Connect 5V power either using a power adaptor such as USB-AC/DC-5+ connected to
the USB port, or supplying power to pin 1 of the D sub connector.
Note:
The USB-1SP16T-83H will start up in disconnected state and assume any state defined by the TTL
controls as long as there is no USB communication. Once USB communication is established
commands via TTL will be disregarded until unit is shut down.
2.3.4.2
TTL communication
The USB-1SP16T-83H TTL control interface consists of 5 unlatched parallel control bits
that select the desired switch state, see model datasheet for truth table. The parallel
control does not have any latch and thus will respond immediately to any change.
Connecting the switch to USB control and establishing USB communication will disable
the TTL control until the switch is reset by disconnecting and then reconnecting power.
All TTL controls are connected with internal pull-down resistors so the default state of the
switch is disconnected state.
The TTL interface is input only providing no feedback on switch state.
Page 14 of 23
AN-49-012 Rev.: (January 10, 2019) M171660 (R94356) File: AN-49-012(B).doc
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