RBRconcerto connection to MLM

The MLM-1000-based RBRoncerto³ C.T.D marine data logger system is factory configured for “out-of-the-box” operation. All that is required is:

a 12V (nominal; 7V-20V minimum and maximum) DC power supply to power the head-end modem (HEM)
a serially (RS-232) connected data port that the HEM utilizes to transmit the system data

The RS232 data link to the HEM has been configured for a baudrate of 19.2kbits / second.
The HEM has been configured to perform a polling cycle at one minute intervals. This can be easily be reconfigured (see below).

Polling mode overview

This modem based CTD logger system operates in an autonomous polling mode. The Head-End-Modem initiates a polling cycle of the system- connected CTD loggers at regular intervals. The polling interval is determined by the configuration of the PINT parameter in the HEM (See below). The polling interval for this system has been factory set to 1 minute, but can easily be changed by following the instructions as per the PINT command below.

During a poll, each logger will produce a sample of the CTD sensors. The sample data is collected by the HEM, consolidated and transmitted to whatever device is connected to the HEM serial port (e.g. RF Modem).

Each sample generated by a logger will have a time stamp as per the real- time clock in the logger. If the logger clock is not initialized, of course the time information should be ignored and the system that receives the polling data shall put it’s own time stamp on the data.

The following is an example of the data transmitted by the HEM after a number of polling cycles (One minute polling interval).

The first number is the serial number of the sub-surface modem that is attached to a given logger. This is followed by the logger’s time and the readings for conductivity, temperature and pressure.

023218: 2012-11-19 18:51:57.000, 0.0003 mS/cm, 21.8801 C, 10.2686 dBar
023211: 2012-11-19 18:51:57.000, 0.0026 mS/cm, 22.0510 C, 10.1721 dBar
023218: 2012-11-19 18:52:57.000, 0.0001 mS/cm, 21.8707 C, 10.2678 dBar
023211: 2012-11-19 18:52:57.000, 0.0021 mS/cm, 22.0431 C, 10.1728 dBar 
023218: 2012-11-19 18:53:57.000, 0.0006 mS/cm, 21.8588 C, 10.2681 dBar
023211: 2012-11-19 18:53:57.000, 0.0023 mS/cm, 22.0364 C, 10.1723 dBar 
023218: 2012-11-19 18:54:57.000, 0.0006 mS/cm, 21.8444 C, 10.2678 dBar 
023211: 2012-11-19 18:54:57.000, 0.0025 mS/cm, 22.0289 C, 10.1717 dBar

Benchtop testing and a “simulated mooring line”

Perform the following steps to set up the system for bench top testing:

connect the HEM to a 12V DC power supply using the supplied power cable
connect the HEM to an RS232 data port using the supplied data cable
connect the Cable Coupler Assembly to HEM with the supplied cable
(Marked CCA on the cable and at the HEM connector)
When performing bench top testing, the user would normally thread a wire loop through the toroidal transformer mooring-line couplers.
It is important to put a resistance in series with the wire loop that simulates conduction through the mooring line.
The value of this resistance should be in the range 20 to 100 ohms.
The system has been configured to:
HEM BAUD rate – 19.2Kbits (See BAUD)
Polling is enabled (See PEN)
Polling interval has been set to 1 minute (See PINT)
Should the user require a different HEM baud rate, it may be selected using theBAUD command when connected to the HEM.
When the HEM sits idle for more than 10 seconds, it will enter sleep mode. Therefore it must be awakened from the sleep state by sending any single character over the serial link to the HEM.
The following is an excerpt from the OEM command reference regarding the BAUDcommand as it pertains to the HEM. (Note that “Default” in the command descriptions refers to the value after a complete reset).

BAUD - Baudrate

Parameter: BAUD
Description: baudrate
Values: 300, 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200 (HEM) Default: 115200 (HEM),

This parameter defines the baudrate of the serial communications port. This will always be with 8 data bits, no parity and 1 stop bit (8-N-1).
Example: EE BAUD 115200<cr>

The other programmable parameter that is of interest to the user is the polling interval. This parameter defines the frequency at which the system polls the CTDs. The following excerpt is from the OEM command reference regarding the PINT – the command that sets the polling interval.

PINT - Poll Interval Time

Parameter: PINT
Description: poll interval time (min)Values: 1-65535

Default: 5
Applies to: HEM
This parameter defines the polling interval of time in minutes. Example: EE PINT 120<cr>
<t>poll interval time (min) PINT: 120<cr><lf>

PNOW - Poll Now

When PNOW is sent to the HEM, it will immediately initiate a polling sequence of the loggers that are attached to the system.

PEN - Poll Enable

Must be set to 1 when autonomous system polling is desired. The system by default is configured to poll.

PEN – Poll EnableParameter: PENDescription: poll enableValues: 0, 1

Default: 0
Applies to: HEM
This parameter defines whether the scheduled polling should be enabled. Once enabled,

Example: EE PEN 1<cr><t>poll enable PEN: 1<cr><lf>