PC-DMIS CMM allows you also define a hard (or fixed) probe. While touch trigger probes (TTP) cause the CMM to report the position whenever the probe comes in contact with the part, a hard probe does not behave this way. Instead, a hard probe registers a hit whenever you press a button on the machine or arm or, in the case of scanning, when certain conditions are met (such as crossing a predefined zone, elapsed time, elapsed distance, and so forth).
Generally, these types of probes are used with PC-DMIS Portable. To calibrate and use this type of probe, see "PC-DMIS Portable" in the PC-DMIS Portable documentation.