| 摘要 |
In order to collect data messages (fig. 6) at a base station (fig. 2) which is in radio communications with portable data collection terminals (fig. 1) such as contain bar code scanners and which may move between different locations, all remote from the base station (fig. 2) in order to scan different labels (12) and read bar codes (10) printed thereon, a set of successive polling messages (fig. 4) are broadcast from the base station (fig. 2) addressed to different ones of the remote units (fig. 1) during successive polling cycles. The rate and the time for completing each polling cycle is optimized by increasing the interval between polls on one of the polling cycles where data is being collected, but only if a response on a previous high speed polling cycle from the remote unit (fig. 1) is coded to represent that unit has data ready to be transmitted to the base station (fig. 2). |
