HP 5100tn Printer Job Language - Technical Reference Manual - Page 209

know which I/O interface to use when sending solicited printer responses. When the printer sharing device sends data to the printer from a different I/O interface, the printer sharing device must know to the exact byte boundary what printer response data should be sent to the previous I/O interface and what data should be sent to the current I/O interface. Before the printer sharing device sends the printer data from a different I/O interface than the source of the current print job, the printer sharing device can inject a PJL ECHO command. All solicited printer responses received before the PJL ECHO response should be sent to the previously active I/O interface. All solicited printer responses received after the PJL ECHO response should be sent to the currently active I/O interface. The printer sharing device should consume the PJL ECHO response which was a result of the PJL ECHO command injected by the printer sharing device. Applications that use unsolicited PJL device, job, page, or timed status need to work properly with printer sharing devices that do not support unsolicited printer-to-host responses. 3. A printer sharing device that can route solicited responses as described in 2 above, plus send all unsolicited responses to all attached host computers. Applications must be designed to properly ignore unexpected printer status readback responses. Ideas on how to design an application to ignore unexpected printer status readback responses are described in the next section. Programming Tips 10-29