NetScanTools Pro v11.42 introduced two major improvements to the Packet Generator scripting:
The first is a 'debugging' window. This new window, located below the main controls on the Packet Generator page serves the primary purpose of showing the command processing during scripting - if you have Enable Script Debugging Messages checked. The other purpose for it is to show certain errors when they occur.
The second improvement is the addition of five new packet reset commands. These commands are intended to be used just prior to modifying packet parameters followed by sending the packets. They reset the TCP, UDP, ICMP, CDP and ARP packet headers to known states - primarily zero. The commands are:
!TCP_RESET_PACKET - resets the TCP header
!UDP_RESET_PACKET - resets the UDP header
!ICMP_RESET_PACKET - resets the ICMP header
!CDP_RESET_PACKET - resets the CDP header and presets some fields to non-zero values
!ARP_RESET_PACKET - resets the ARP header and presets some fields to non-zero values
This is detailed in the Help file (press F1 while viewing the Packet Generator) under the topic Packet Generator - Scripting.
Be sure to use these before defining header parameters and sending packets.