Synchronization using Clear To Send (CTS) and Request To Send (RTS) signals
In many applications, the synchronisation interface is based on an RS-232 serial port. Only the Clear to Send (CTS) and Request to Send (RTS) connections of the RS-232 interface are then used.
According to the standard specifications for RS-232, an output must generate a voltage level of +5 to +15 VDC (logic "low"), and -5 to -15 VDC (logic "high") into a load of 3 to 7 kΩ. An RS-232 receiver must present a 3 to 7 kΩ load , converting an input of +3 to +25 VDC to logic "low", and an input of +3 to +25 VDC to logic "high". With a positive trigger pulse, the offset voltage does not have any significance. Even small variations (flutter) over and below 0 VDC will not trigger the interface.
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A Local connection
B Connection on remote device
C Female 9-pin D-Subminiature connector
D Male 9-pin D-Subminiature connector
Note
RS-422 communication ports can not be used for synchronization purposes. The port you wish to use must be set to RS-232.