Graphics Options and Device Parameters Dictionary

HANDSHAKE

Specifies the type of flow control used to regulate the flow of data to a hard copy device.

Used in:	GOPTIONS statement; GDEVICE procedure; GDEVICE Parameters window
Default:	host dependent
Restriction:	not supported by Java or ActiveX

Syntax
Details

Syntax

HANDSHAKE=HARDWARE | NONE | SOFTWARE | XONXOFF

HARDWARE HARD: specifies that SAS/GRAPH instruct the device to use the hardware CTS and RTS signals. (This is not appropriate for some devices.)
NONE: specifies that SAS/GRAPH send data without providing flow control. Specify NONE only if the hardware or interface program you are using provides its own flow control.
SOFTWARE SOFT: specifies that SAS/GRAPH use programmed flow control with plotters in eavesdrop mode.
XONXOFF X: specifies that SAS/GRAPH instruct the device to use ASCII characters DC1 and DC3. (This is not appropriate for some devices.)

Details

HANDSHAKE regulates flow of control by specifying how and if a device can signal to the host to temporarily halt transmission and then resume it. Flow control is important because it is possible to send commands to a hard copy device faster than they can be executed.

HANDSHAKE can be used when you are using a protocol converter, interface program, or host computer that can perform XONXOFF or hardware handshaking. You can also use this option if you are routing output through flow-control programs of your own, as in a multiple-machine personal computer environment where the graphics plotter is a shared resource. SAS/GRAPH software sends output to a server (the file transfer does not require flow control). The server queues incoming graphs and sends them to the plotter. The server, rather than SAS/GRAPH software, is responsible for handling flow control. An interface program is usually invoked by the line printer daemon and provides formatting or control signals for a system destination. The interface program typically includes port configuration options, such as baud, parity, and special character processing requirements (raw or cooked mode) for that destination.

If you do not use HANDSHAKE, the value in the driver entry is used.

If you use HANDSHAKE=XONXOFF or HANDSHAKE=HARDWARE, SAS/GRAPH does not actually do the handshaking. It tells the device which type of handshake is being used. The protocol converter, interface program, or host computer actually does the handshake.

Note: If you are creating a graphics stream file using a driver for a plotter and you specify HANDSHAKE=SOFTWARE, the software that you use to send the file to the plotter must be able to perform a software handshake. You will probably want to specify one of the alternative values if you route output to a file. [cautionend]

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