HP 5100 Printer Job Language - Technical Reference Manual - Page 211

query and one generated because of the resent query). If the application is using an outstanding solicited query list, then when the first response is received, the query will be removed from the list. When the second response is received, the second response will be ignored because there is no matching query in the outstanding solicited query list. Given the above structure for sending queries and processing responses, applications should adhere to the following guidelines: 1. If the application sends data to the printer in blocks, followed by long pauses between blocks (i.e. greater than five seconds), then it should cause the printer to use a larger I/O interface idle time value by using the PJL JOB command as described in the "Printer Status Readback and Printer I/O Switching" section. 2. Check status readback availability as described in the "Determining if Printer Status Readback is Available" section. 3. Synchronize with the printer-to-host data stream as described in the "Old Printer Status Readback Responses" section. 4. Do not have more than five outstanding queries before accepting printer status readback responses. This prevents response data loss as described in the "Response Data Buffer Overflow" section. 5. Before quitting, turn off all unsolicited status enabled by the application. Also, accept all responses from the printer that were generated because of actions performed by the application. 6. Do not be dependent on the timing characteristics of a single printer model. For example, the response time of the HP LaserJet 4 printer's built-in Bi-Tronics I/O interface will be different than the timing characteristics of a Bi-Tronics I/O interface in an I/O card installed into the printer. Programming Tips 10-31