Q. What is the difference between a port and an instrument?
A. QS-Pro treats all measuring tools equally and manages the differences in capability from one tool to the next by means of ports and instruments. A port is basically a connection point on your computer for a measuring tool to be plugged in and used with QS-Pro. A QS-Pro instrument is a named object in the software that, ideally, provides a stream of calibrated measurement data for QS-Pro to display and store. An instrument is always linked to a port as it's ultimate source of measurement data.
The number of ports in your computer is determined by the physical interfaces it has (RS232 connectors, interface cards etc) and the software drivers you have installed. If you have a single Cadar PCI LVDT Interface card AND have installed the driver software for it, then QS-Pro will show 16 LVDT probe ports as being available. If your PC has two RS232 connections and you also load the driver for, say, the Cadar Microstat micrometer, then QS-Pro will show two more ports - for a Microstat in COM1 and one in COM2.
The number of instruments in your system is determined by you. You can create as many as you like but each one must be linked to a port if it is to give you data from a physical measuring tool. You can define a number of instruments linked to the same port. Suppose you have two gauges each with 10 probes but have only one probe interface card (supporting up to 16 probes). That's fine as long as you don't want to use both gauges at once. Define ten probe instruments, say Probe01 to Probe10, for you first gauge and link them to the first ten ports on your interface card. You can calibrate them to account for sensitivity and gain etc. and then create a batch using those instruments as data sources and use the gauge to measure parts.
Next day you need to use the other gauge so you unplug the first and plug in the second. But this gauge uses different types of probes and needs its own calibration. Fine - define some new probe instruments, say Probe11 to Probe20, link them to the same ten ports as Probe01 - Probe10, and calibrate them in the usual way. Create a new batch that uses these new instruments and start measuring parts. When you need to use the first gauge again you unplug the second one, plug in the first, open the batch you created for that gauge and you're ready to measure. QS-Pro remembers the calibration of Probe01 to Probe10 from last time and uses them again.
Put another way, the port produces a stream of numbers from a measuring tool, the instrument knows what those numbers mean.
Things can blur slightly. If you now install the QS-Pro driver for a Mettler weigh scale, which also uses RS232, then QS-Pro will see two more ports representing COM1 and COM2 but this time for Mettler scales. You can plug in either a Microstat or Mettler scale into COM1 but clearly not both at once! To use the Microstat in COM1 you must define a QS-Pro instrument linked to the Microstat port for COM1. To use the scale in COM1 you must define an instrument linked to the scale port for COM1. If you plug in the Micorstat and then try to use a batch reading the scale instrument then QS-Pro will get no data because the scale driver software cannot interpret the Microstat data (and vice versa). A port is really the combination of a physical connector and a software driver to interpret the data.