This timer, in milliseconds, controls how often the SSCOP (QSaal) layer on this port sends a POLL PDU to solicit a STAT status report from the far end, independent of the MaxPD PDU-count trigger, per the description. It's the time-based half of SSCOP's dual polling strategy, ensuring the link still exchanges status even during periods of low sequenced-data traffic where the PDU-count trigger would rarely fire. A typical TPoll value of a few hundred milliseconds keeps loss detection responsive even on an otherwise idle signaling channel.