5.1 Acknowledge Active Command: a!

This command is used to ensure that an WLTS is responding to the SDI-12 recorder. A typical command/ reply would be: 0!/0<CR><LF> where the '0's represents the WLTS SDI-12 device address and <CR> represents a carriage return (Hex 0D) and <LF> represents a line feed (Hex 0A). All replies from an WLTS are terminated with <CR><LF>. All SDI-12 recorder commands are terminated with an exclamation mark '!' character.