Teledyne Oceanscience rapidCAST, User Manual

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March 2018 rapidCAST User’s Guide
Page 48
EAR-Controlled Technology Subject to Restrictions Contained on the Cover Page.
Using Auto-Depth
If Auto-Depth is enabled, the target depth is automatically set via NMEA 0183 messages from a depth
sounder. DBT, DPT, DBK, and DBS sentences are supported. Serial communication is the supported
transmission protocol in this initial release. NMEA messages may be input to the rapidCAST Interface via
a physical serial port or a virtual serial port.
In cases where rapidCAST Interface and the hydrographic survey software both reside on the same PC, a
virtual serial port may be the easier option to implement. If the survey software is already receiving
NMEA messages to perform its job, and if it has data re-broadcast capability, the survey software may re-
gurgitate the NMEA data through a virtual serial port, which rapidCAST Interface can connect to, without
requiring physical cabling.
Third-party software can be used to create virtual serial ports. This feature has been successfully tested
with EIVA NaviScan survey software working in conjunction with virtual serial ports provided by Eltima
Software, for example.
What Auto-Depth Does and Does Not Do
Enabling Auto-Depth simply allows the NMEA stream to automatically populate the “Nominal Target
Depth” field as depth readings are received on-the-fly. For operational safety, it does NOT automatically
deploy the probe without human authorization. An operator must still decide when to start the deploy-
ment sequence.
Nominal Target Depth is updated as each valid depth reading is received. This happens continuously until
the tension-controlled deployment has started to ensure that the newest depth information is used up to
the moment it is needed. Once probe freefall has started, a “Paused for Deployment” status message will
indicate that the Nominal Target Depth is intentionally left unchanged for the duration of the cast, so that
the user knows the depth that is being targeted. When the cast is finished, NMEA messages will resume
updating the target depth.