Seametrics DO2, Instructions Manual

DO2 INSTRUCTIONS

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Page 18 seametricscom

There is a “power on” register on the DO2 (register 62720 or 0xF500).  When a  

positive value “n” is written to this register, the power is turned on to the sensing 

probe and remains on for n/4 seconds. When a reading is requested, the timer 

is reset and the sensing element remains on for another n/4 seconds. To force 

the power off immediately after a reading, for power savings, write a zero to the 

register. If the power to the entire DO2 sensor is turned off, this value defaults to 

30 (or 7.5 seconds).
Recommendations to ensure proper warm-up/stabilization and to conserve power:

•  Write Power On value of  30 (30/4 = 7.5 seconds)

•  Power turns on

•  Starts sampling about two times per second

•  Wait 7 seconds then request a reading

•  Returns most recent sample

•  Resets Power On value to 30 (30/4 = 7.5 seconds)

•  Write Power On value of 0 (zero)

• 

Turns power off

•  Retains last reading

• 

If you Cannot Write to the Power On Register

If you are reading your device using a meter or other device that cannot write the 

Power On but simply takes readings on a specified schedule, be sure to set the 

polling interval to less than 7.5 seconds. This will ensure that the sensing probe 

is always powered up and readings should be fresh and stable. Note that the first 

reading when you turn on the sensor and meter will be old but will refresh within 

a second or two. 

For further information and detailed Modbus examples, see Seametrics application 

note,  “

Modbus Direct Read on Smart Sensors

” available from our web site at  

www.seametrics.com.

Reading Via SDI-12

Addressing

Default SDI-12 Address: 0

SDI-12 Command Nomenclature

<a> = Sensor address

{crc} = SDI-12 compatible 3-character CRC

<cr> = ASCII carriage return character

<lf> = ASCII line feed character

highlighted values

indicate variable data

SDI-12 Commands

//*** Sensor Identification

<a>I! <a>13  INWUSA  SMDO

2.01

ssssssssss

<cr><lf> 

APPENDIX C: READING THE DO2 VIA DIRECT READ