Graphics Options and Device Parameters Dictionary

PROMPTCHARS

Selects the prompt characters to be used by SAS/GRAPH device drivers.

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

Syntax
Details

Syntax

PROMPTCHARS='prompt-chars-hex-string'X

prompt-chars-hex-string

is an 8-byte hexadecimal string that is specified as 16 hexadecimal characters. In GDEVICE procedure statements, enclose the string in single quotation marks, followed by an X. In the Parameters window, enter the hexadecimal string without either quotation marks or a trailing X.

Note: Bytes 1, 4, and 5 are the safest for you to change because you are most likely to know the correct value for them. Check with Technical Support before changing any of the other bytes. [cautionend]

The following list describes each byte in the string:

byte 1

is the ASCII code of the system prompt character (for software handshaking). The system prompt character is the last character that the host sends before waiting for a response from the plotter. For example, 11 means the host sends an XON or DC1 character as a prompt. If the host does not send a special character for a prompt, set this byte to 00.

byte 2

is the ASCII code of the echo-terminator character (for software handshaking). This character is sent at the beginning of each record.

byte 3

prevents splitting commands across records if the value is 01. If you are creating a graphics stream file to send to a device at a later time, and there is the possibility that extra characters will be added between records during transmission, setting the third byte to 01 reduces the likelihood that the extra characters will be interpreted as graphics commands and cause stray lines or other device characters. If the third byte is set to 00, the driver makes the records as long as possible and splits device commands across records if necessary. Setting the third byte to 00 is more efficient but is more likely to result in device errors if output is written to a file and later transmitted to the device.

byte 4

is the line-end character (for software handshaking). It indicates that more data can be sent. This character is almost always a carriage-return character, 0D.

byte 5

specifies turnaround delay in tenths of a second (for software handshaking). The turnaround delay is the amount of time the device waits after receiving the prompt character before sending the line-end character. For example, a value of 05 represents a half-second delay.

byte 6

sets default record length using a hexadecimal value 00-FF. This byte sets the length of the records sent to the device or to a file. If this byte is set to 00 (the default), SAS/GRAPH uses the longest record length possible for the device. To specify an alternate length, set the sixth byte to the hexadecimal value for the desired length. For example, to generate records of length 80, specify 50 for the sixth byte. If the GSFLEN device parameter or graphics option is specified, its value overrides the value of the sixth prompt character.

Some values of the GPROTOCOL device parameter cause each byte in the data stream to be expanded to two bytes. This expansion is done after the length of the record is set by PROMPTCHARS. If you are specifying a value for GPROTOCOL that does this (for example, SASGPHEX, SASGPLCL, or SASGPAGL), specify a value for the sixth byte of PROMPTCHARS that is half of the actual record length desired. For example, a hexadecimal value of 40 (64 decimal) produces a 128-byte record after expansion by the GPROTOCOL module.

bytes 7 and 8

are unused and should be set to 0000.

Details

PROMPTCHARS is most commonly used to specify parameters used in software handshaking (see HANDSHAKE), but it can also be used to control the length of records written by most drivers. You can also use the GSFLEN= graphics option for this purpose.

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