Seametrics GDL Manuale utente

PROUDLY

MADE

IN THE

USA

ISO

9001:2008

Precision Environmental Sensors

An ON

CON Brand

GDL 4-20 mA

Datalogger

Instructions

GDL 4-mA INSTRUCTIONS

Seametrics • 253.872.0284 Page 2 seametrics.com

General Information ...........................................................................................4

What is a GDL?..........................................................................................................................................4

Initial Inspection and Handling ..........................................................................................................4

Do’s and Don’ts........................................................................................................................................4

Getting Started.....................................................................................................5

GDL Connectors .......................................................................................................................................5

Connecting Your 4-20 mA Devices to the GDL............................................................................5

Connecting GDL to Computer............................................................................................................5

Aqua4Plus Software................................................................................................................................6

Warm Up Time..........................................................................................................................................6

User Dened Units ..................................................................................................................................6

Maintenance .........................................................................................................9

Changing Batteries..................................................................................................................................9

Reading the GDL ............................................................................................... 10

Setting Units for Direct Read............................................................................................................ 10

Reading Via Modbus®RTU ............................................................................................................... 11

Reading Via SDI-12 .............................................................................................................................. 12

Appendix A: Specications .............................................................................. 15

Channel Specications........................................................................................................................ 15

Power Supply.......................................................................................................................................... 15

Enclosure.................................................................................................................................................. 15

Communication Connector............................................................................................................... 15

Appendix B: Alternate Connection Options................................................... 16

Connecting via RS232 Serial Port ................................................................................................... 16

Connecting with a USB/Serial Adapter......................................................................................... 16

Limited Warranty/Disclaimer - GDL Data Logger.......................................... 18

trademarks belong to their respective owners.

TABLE OF CONTENTS

GDL 4-MA INSTRUCTIONS

Seametrics • 253.872.0284 Page 3 seametrics.com

What is a GDL?

Seametrics GDL is a datalogger to which analog sensors can be attached and then read

from Seametrics Aqua4Plus control software. It takes the analog signals and converts them

into digital signals. The GDL board can read the sensors in real time or record sessions

of data for later upload. This industry standard digital RS485 interface device records

thousands of records, operates on low power, and features easy-to-use software with

powerful features.

This particular unit is a GDL with two 4-20 mA channels. Output can be displayed in mA,

microAmps, or user-dened units.

The GDL is powered with eight AA batteries The unit is programmed using a laptop

or desktop Windows®based computer via its RS485/RS232 connector and easy to use

Aqua4Plus software. Once programmed the unit will measure and collect data on a variety

of time intervals.

Initial Inspection and Handling

Upon receipt of your datalogger, inspect the shipping package for damage. If any damage

is apparent, note the signs of damage on the appropriate shipping form. After opening

the carton, look for concealed damage. If concealed damage is found, immediately le a

claim with the carrier.

Do’s and Don’ts

• Do handle the device with care.

• Don’t install the device such that the box or any of its connectors are

submerged.

• Don’t support the device with the connector or with the connectors of an

attached cable.

• Don’t bang or drop the device on hard objects.

GENERAL INFORMATION

GDL 4-mA INSTRUCTIONS

Seametrics • 253.872.0284 Page 4 seametrics.com

GDL Connectors

This GDL comes with three connectors - two for connecting 4-20 mA devices and one

communication connector for connecting to the computer.

The GLD has one communication connector and a variable

number of sensor connectors, depending on your conguration.

Connecting Your 4-20 mA Devices to the GDL

Connect your 4-20 mA devices to the sensor connectors.

Pin 1 12 Volts

Pin 3 Signal return

Pin 5 GND

Connecting GDL to Computer

Connect the GDL to your computer’s USB port, as shown below. Drivers and instructions

come with the adapter. (For alternate connection options, see Appendix C.)

Connect the sensor to your PC using Seametrics’ USB to RS485 adapter. (See Appendix C for alternate

connections.)

Aqua4Plus Software

The GDL comes with the Aqua4Plus host software that is installed on your PC or laptop.

This software is used to program the datalogger, to retrieve data from the logger, to view

collected data, and to export data to external les for use with spreadsheets or databases.

Refer to the Aqua4Plus software manual for details on installing and using Aqua4Plus.

Communication

Connector

Sensor

Connectors

PC or Laptop

USB Port

USB to RS485

Adapter

GDL

GETTING STARTED

GDL 4-MA INSTRUCTIONS

Seametrics • 253.872.0284 Page 5 seametrics.com

Warm Up Time

Many analog sensors require a warm-up time before readings are stable. The GDL board

has a programmable eld for warm-up time. (Note: the GDL reads all channels each time it

takes a reading. Therefore, this warm-up time should be set to the longest warm-up time

needed by the particular sensors you have connected, even though some may require a

much shorter warm up time.)

Set this warm up time by clicking on Warm Up Time... on the Congure menu.

User Dened Units

In addition to normal unit selections, the 4-20 mA channels have a User Dened option.

For instance, normally a 4-20 mA channel would have mA and microAmps as units options.

If the user has a pressure sensor connected to a 4-20 mA channel, output may be desired

in psi. For that there is a User Dened Units option.

Congure User Dened Units as follows:

1. Connect your GDL box to the computer and start Aqua4Plus.

2. Scan for sensors and select the GDL. (Refer to the Aqua4Plus software manual for

details on using Aqua4Plus.)

3. In the Display Units box (under the Options menu), there are three entries for

4-20 mA channels – mA, uA, and User Dened. Select User Dened.

4. You can only set eld calibration when there are no sessions on the GDL. Be sure to

upload any data on the sensor and erase all sessions, before continuing.

5. From the Congure window, select Field Calibration. (Refer to gure on next page

for an illustration of Field Calibration window.)

6. In the left panel, highlight the channel you want to congure. Each channel can have

its own user dened units. For example, if you have the rst channel connected to

a pressure sensor, you might want those units to be psi. If you have the second

channel connected to a temperature sensor, you might want those units in degrees

Celcius.

Select User Dened Units

GETTING STARTED

GDL 4-mA INSTRUCTIONS

Seametrics • 253.872.0284 Page 6 seametrics.com

7. Dene your own user units in the Field Calibration window as follows.

• User Units: Enter a name for your units in the User Units box. For example, you

might enter psi.

• Scale: Compute the scale value as follows:

(Total range of measurement in your units) / 16 / 1000

For example: if you want to measure 0 – 15 psi:

15 / 16 / 1000 = .0009375

Enter this value in the box labeled Scale.

• Oset: Compute the oset value as follows:

minimum user units - (scale * 4000)

Using our 0 – 5 psi example above, this would be

0 - (.0009375 * 4000) = -3.75

Enter this value in the Oset box.

• Dec Places: Enter the number of decimal places you want displayed during

readings.

• Min and Max: Enter the minimum and maximum values for your new units.

(These values will dene the limits on data graph.)

• Comment: If desired, enter a comment in this box.

8. Click OK to save to the sensor.

Congure User Dened Units on the

Field Calibration Window

GETTING STARTED

GDL 4-MA INSTRUCTIONS

Seametrics • 253.872.0284 Page 7 seametrics.com

Changing Batteries

Because changing the batteries involves opening the weather-tight seal, this must be

done in a clean, dry environment to avoid contamination or moisture damage to

the circuitry.

The GDL runs on eight AA alkaline batteries.

To replace the batteries, remove the four corner screws and lift o the lid. Gently lift out

the battery pack. Replace the batteries, and then place the lid on the box, tightening

the screws securely. NOTE: The box is directionally keyed. Failure to replace the lid

correctly will prevent a tight seal and will result in water leakage.

Note: keyed slot in box before replacing lid.

No slot Slot

MAINTENANCE

GDL 4-mA INSTRUCTIONS

While the GDL comes with the easy to use Aqua4Plus software, you can also use standard

Modbus®RTU or SDI-12 equipment to easily take readings, so as to tie into your existing

equipment or networks.

You may need to use Aqua4Plus to make a few settings, prior to directly reading the GDL

with your equipment. These settings may include units for returned values, baud rate, and

SDI-12 command structure. These are described in the following sections.

Setting Units for Direct Read

By default, the 4-20mA channels return readings in mA.

However, you can select from a variety of units for direct read measurements. If you want

to change to dierent units. Set these units using Aqua4Plus.

1. Click on the Congure menu, and then select Advanced.

2. From the yout menu, select Direct Read Units.

3. On the popup box, click the down-arrows next to 4-20mA, and then select the units

you want.

4. Click OK

Use Aqua4Plus to select the units for your direct

read measurements, whether Modbus or SDI-12.

Once set, these units are saved on the sensor and direct readings, either via Modbus or via

SDI-12, will return values using these units. (Note: These settings do not aect the units

used on the Aqua4Plus display. Refer to the Aqua4Plus software manual for details on

using Aqua4Plus.)

Seametrics • 253.872.0284 Page 8 seametrics.com

READING THE GDL

GDL 4-MA INSTRUCTIONS

Reading Via Modbus®RTU

Baud Rate

Your GDL comes congured to communicate at 38,400 baud, with 8 data bits, one stop

bit, and no parity. The logger can also be set to 19,200 or 9600 baud, if needed for

your application. If needed, set your GDL to the desired baud rate using Aqua4Plus, per

instructions earlier in this manual.

Taking Measurements

Read measurements using Modbus function 03 – Read Holding Registers.

Readings are located in two registers each. (GDL register address is zero based, i.e., starts

at zero. If your equipment uses one based addressing, you will need to add one to the

Table 1: Register addresses for GDL Data Logger

Addresses for standard channels

Zero Based One Based

4-20 mA 1 62602 62603

4-20 mA 2 62604 62605

For further addressing information and detailed examples, please go to our website:

seametrics.com

The data is returned as 32-bit IEEE oating-point values, high word rst, also referred to

as big-endian or oat inverse.

GDL’s Power On Function

Some devices require a warm-up or stabilization time after application of power before

accurate readings can be taken. The GDL provides a means to explicitly turn power on

or o to the analog circuit and any devices attached to the switched power output prior

to requesting a reading. This same function allows you to specify how long the circuit

remains on after a reading has been taken.

There is a “power on” register on the GDL (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 o immediately

after a reading, for power savings, write a zero to the register. If the power to the entire

GDL sensor is turned o, this value defaults to 30 (or 7.5 seconds).

Seametrics • 253.872.0284 Page 9 seametrics.com

READING THE GDL

GDL 4-mA INSTRUCTIONS

The recommended procedure to ensure proper warm-up/stabilization and to conserve

power is:

1. Write Power On value of 30 (30/4 = 7.5 seconds) *

• Power turns on

• Starts sampling about two times per second

2. Wait 7 seconds then request a reading *

• Returns most recent sample

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

3. Write Power On value of 0 (zero)

• Turns power o

• Retains last reading

* If your attached sensors have a longer warm-up/stabilization time, increase these values.

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 specied schedule, be sure to set the polling interval

to less than 7.5 seconds. This will ensure that the GDL is always providing power to the

connected sensors and readings should be fresh and stable. Note that the rst reading

when you turn on the sensor and meter will be old but will refresh within a second or two.

Reading Via SDI-12

Addressing

Default SDI-12 Address: 0

Channel Setup Using Aqua4Plus

Standard SDI-12 commands are limited to returning a maximum of nine values. The GDL,

depending on how it is congured, may have as many as 15 channels. For this reason,

Aqua4Plus contains an SDI-12 setup utility to allow you to dene which channels are

returned for the M or C, M1 or C1, M2 or C2, and M3 or C3 commands.

Open the SDI-12 setup utility from Aqua4Plus by clicking on the Congure Menu and then

selecting Advanced. From the yout menu, select SDI-12 Setup.

Seametrics • 253.872.0284 Page 10 seametrics.com

READING THE GDL

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