Star Micronics 150 Serial Mode Inquire, Parallel, Ieee 1284 Mode Inquire, Dynamic Response Mode

Control Codes PcOS Series 150 Programmer's Guide

Printer Status Set/Inquire

Receipt paper status is always dynamic. If the PE signal is to be returned to the valid paper error state, an [ENQ] <4> should be issued when all other inquires are completed.

PE		Valid
DATA	ID	Next
STROBE
BUSY
ACK

Figure 13 Paper-error to inquire-request timing

Serial Mode Inquire

In serial mode, inquires are not handled any differently than other commands. All inquire commands require a response from the printer and are responded to by an acknowledged (ACK) or not acknowledged (NAK) and then the command ID.

The serial ACK or NAK responses are always uniform and followed with a command ID. This makes the design of the host application easier because the response can be identified and the same format is always followed.

The printer always accepts serial data. When the printer is off-line, serial data is still accepted. It is possible to send inquire commands to the printer even if it is off-line. Because inquire commands are processed before they go in the buffer, the printer will respond even when it is busy printing.

In serial mode, it is desirable that the response to an inquire be received by the host before another inquire command is issued to the printer. When the printer receives an inquire, it must generate a response. If inquires are sent to the printer too fast, the printer could overrun its output buffer.

Parallel, IEEE 1284 Mode Inquire

In parallel, IEEE 1284 mode, there is a way to return status information to the host. After the host makes an inquire request, the host can activate parallel, IEEE 1284 Mode 0 reverse channel and wait for a response from the printer. The response to the inquire is identical to serial mode.

The printer will always accept IEEE 1284 reverse channel requests but will not accept inquire commands when off-line. It is possible to obtain status when off-line by placing the printer in dynamic response mode before the printer goes off-line. The IEEE 1284 reverse channel will then respond to status changes even if the printer is off-line.

Dynamic Response Mode

Dynamic status, [ESC] w <n>, can be used to allow the host to sense status changes without sending repeated inquiry commands. The operation of the dynamic response varies depending on the configuration of the printer. If the printer is configured for serial or parallel, IEEE 1284 operation, more than one status can be sensed as the printer will respond to status changes as if

Page 60 Rev G 12/14/99