|Graphics Options and Device Parameters Dictionary|
|Used in:||GOPTIONS statement; GDEVICE procedure; GDEVICE Parameters window|
|Restriction:||not supported by Java or ActiveX|
|HANDSHAKE=HARDWARE | NONE | SOFTWARE | XONXOFF|
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 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.