Options

Your printer's Telnet interface supports four Telnet options:

  • Binary
  • Suppress-Go-Ahead (SGA)
  • Echo
  • Status

In accordance with the Telnet specification, the printer's Telnet server sets each of these options off and assumes the client has done likewise. Telnet connections are full duplex, and options are negotiated separately for each half of the connection.

Binary option

The Telnet interface defaults to NVT mode. One implication of this is that only 7-bit ASCII data can be transmitted from client to server and from server to client. The Binary option enables the transmission and reception of 8-bit data (character values 00H-FFH.)

The Raw, BCP, and TBCP protocols transmit data with values in the 00H- FFH range. The Normal protocol transmits data only in the range 00H-7FH. Rather than renegotiate the Binary option each time the Protocol parameter is changed, the server attempts to move both halves of the connection permanently to the binary mode shortly after connection.

If for any reason the server cannot successfully negotiate or remain in Binary mode, then all data sent or received via Telnet will be truncated to 7 bits (the MSB of each byte is zero). It is therefore strongly recommended that clients follow these guidelines:

  • Do not refuse to enter Binary mode.
  • Do not attempt to exit Binary mode. If the client exits Binary mode, the Telnet server agrees to exit binary mode; however, this results in truncated data (the most-significant bit of each byte is zero).

Suppress-Go-Ahead option

If the client wants the printer's Telnet server to suppress go-aheads, the server does so; it also honors requests to disable the Suppress-Go-Ahead option. The server never requests that the client suppress go-aheads. However, if the client offers to suppress go-aheads, the Telnet server accepts the offer.

Echo option

By default, server echo is disabled. If the client requests the printer's Telnet server to echo, the server accepts the request. The server never requests that the client echo data, and it refuses a client offer to do so. To avoid unnecessary network traffic, it is strongly recommended that clients follow these guidelines:

  • Enable local echo
  • Do not enable server echo

Status option

If the client requests that the printer's Telnet server enable status handling, the server accepts the request. Once the Status option is enabled, the server responds to status request messages and reports the settings of the four supported Telnet options (enabled or disabled). The server never transmits status information except in response to a client SEND STATUS request. The server silently discards client status advertisements.

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