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Integrator's Guide12

commands sent for 120 seconds, the FTP connection will terminate and the instrument will return

to measurement mode.

For an example on how to configure the instrument to output a telemetry file and download the

file to FTP, check out the next section.

3.3.4 HTTP

HTTP (Hypertext transfer protocol) can also be used for data transmission. For organizations with

strong security / firewall restrictions, FTP access to the instrument may not be permitted. For that

reason, a web page allowing individual data files to be downloaded has been implemented in the

Ethernet processor. The web page can be accessed by clicking on the “Data Download (HTTP)” link

from the main web page.

3.3.5 UDP

UDP (user datagram protocol) can also be used for data transmission. When using UDP, the data

collection software simply waits for data to be sent from the instrument without having to

establish a connection first. This may be useful for cases in which instrument power is

intermittently interrupted and re-connecting to the instrument is not desirable. One downside

to UDP communications is that transmission of the data is not guaranteed. On a noisy / error-

prone connection, it is possible that the occasional datagram may be dropped. If every data

record must be received, then TCP is recommended.

In order to use UDP in a power-safe configuration, the IP address of the data collection software

and port must first be configured using the web interface. The IP address identifies the client to

which the data is to be sent and the port may be used to uniquely identify the instrument to the

application. The same port may be used for all instruments if the data collection software

examines the IP address of the received datagram to identify the instrument. Once this

information has been configured, the Ethernet processor will automatically send real-time data

records to the configured address / port. An instrument in measurement mode re-enters

measurement mode shortly after a power-cycle, so the data collection software will immediately

receive new data without having to re-establish a connection.

3.3.6 PTP

Precision Time Protocol (IEEE-1588) is a standard used for distributing a high-resolution absolute

time throughout an Ethernet network. The Signature series instrument can be configured to act

as a slave to an existing PTP master clock (customer supplied) located in the same Ethernet LAN.

The instrument contains a high-resolution clock which is synchronized and conditioned using PTP

when enabled. The timestamps contained within the data records are then generated from this

clock. When synchronized, these timestamps are typically aligned to within ~10 microseconds.

The PTP master clock must use UDP (layer three) and be configured for two-step operation with

an end-to-end delay mode in order to be compatible with the Signature series PTP

implementation. Using PTP does not affect the choice of UDP or TCP for the transport of data.

Type	Acoustic Doppler Current Profiler (ADCP)
Operating Temperature	-5°C to +45°C
Storage Temperature	-20°C to +60°C
Temperature Sensor	Integrated
Pressure Sensor	Integrated
Compass and Tilt Sensor	Integrated
Data Storage	Internal memory
Communication Interfaces	Ethernet, RS-232
Depth Rating	Up to 6000 meters (depending on model)
Data Output	ASCII, binary
Beam Angle	Varies by model
Velocity Accuracy	±0.5% of measured velocity ±1 mm/s

Nortek Signature Series User Manual

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