Measurement Computing Serial488A - Manual (Page 20)

2.10
2.3.6 Serial Handshake Selection
Switch SW1-5 is used to select between hardware [RTS/CTS] or
software [Xon/Xoff] serial handshake control.
With Xon/Xoff, the Serial488A issues an Xoff character [ASCII value
of $13] when its buffer memory is near full. When issued, there is greater
than 1000 character locations remaining to protect against buffer overrun.
When it is able to accept more information it issues an Xon character
[ASCII value of $11]. The Serial488A also accepts Xon/Xoff on transmit
from the serial host it is communicating with. RTS/CTS serial control
becomes inactive when Xon/Xoff is enabled. The RTS output is, however,
set to an active high state. The CTS input is not used for this handshake
and may be left floating (unconnected).
With RTS/CTS, the Serial488A un-asserts RTS (low) when its buffer
memory is near full. When un-asserted, there is greater than 1000 character
locations remaining to protect against buffer overrun. When it is able to
accept more information it asserts (high) RTS. The Serial488A will not
transmit data to the serial host if it detects the CTS input un-asserted (low)
when configured for this hardware handshake.
The factory default serial control is hardware, RTS/CTS.
SW1 View for Serial Handshake Selection
OPEN
1 2 3 4 5 6 7 8 DOT
Switch
Side
View
OPEN
1 2 3 4 5 6 7 8
RTS/CTS Xon/Xoff