ADU72 USB to Current Input Interface ( 4-20mA, 0-20mA Receiver )

The ADU72 USB to Current Input interface enables measurement of  4-20mA and 0-20mA signals from standard process transmitters via a single USB connection. The ADU72 internally generated 24VDC loop supply eliminates the need for an external loop power supply allowing direct connection of 2-wire process transmitters. This low-cost USB to Current Input Interface is easy to use with VB, and Visual C++ or .NET via standard HID drivers included with Windows 98,2000,XP,7,8,10. A mini-driver ( DLL )* is also provided allowing control using standard ASCII commands using familiar readfile , writefile commands. The ADU72 includes a 10' USB cable and is available in a flange mount enclosure with a DIN rail mount option.

IMPORTANT: The ADU72 requires the use of the Aduhid.dll V2.0.  See bottom of this page for download links.

Command Summary

There are three commands available for the ADU72.  Each command returns the present measured current in either, DECIMAL, CURRENT or HEXIDECIMAL format.

RD               Returns present input current in DECIMAL format ((ASCII STRING-5 BYTES ) 00000 - 65535 representing 0 to 20mA )

RI                Returns present input current in CURRENT format (( ASCII STRING-6 BYTES )  00.000 - 20.000 mA )

RH               Returns present input current in HEXIDECIMAL format ((TWO HEX BYTES )  0000 - FFFF representing 0 to 20mA )

Reading Input Current

The RD command returns the present current in DECIMAL format. The returned integer value ranges from 00000 to 65535. Actual current can be calculated using the following formula;

Reading/65535 X 20 = Current in mA

For example;

RD

returns...

17348                   

Current is 17348/65535 X 20 =5.2942 mA

NOTE: The RD command returns 5 bytes with leading zeros. Remainder of 63 byte packet is padded with nulls.

The RI command returns the present current in CURRENT  format. The returned value ranges from 00.000 to 20.000 and is measured in mA

For example;

RI

returns...

12.347                   

Current is 12.347 mA

NOTE: The RI command returns 6 bytes with leading zeros in the following format nn.nnn . Remainder of 63 byte packet is padded with nulls.

The RH command returns the present current in HEXIDECIMAL  format. The returned value ranges from 0000 to FFFF. Actual current can be calculated using the following formula:

Reading/FFFFh X 14h = current in mA  ( Note that HEX14 = 20 in DECIMAL )

For example;

RH

returns...

A04D                 

Current is AO4Dh/FFFFh X 14h = 12.5236mA

NOTE: The RH command returns 2 bytes with leading zeros in the following format MSB LSB . Remainder of 63 byte packet is padded with nulls.

Notes to Operation:

1. Maximum recommended sample rate is 500 samples per second.

2. Commands are case insensitive.

3. Actual USB control data packets are 64 bytes for full-speed devices.  The ADUHid.dll uses the first byte for internal use resulting in the 63 available byte size.

ADU72 Test Software and V2.0 DLL

The ADU72 is a Full Speed USB product and requires the use of the new Aduhid.dll Ver 2.0 or higher.

The V2.0 DLL and V2.0 AduHidTest Software can be downloaded here:

ADUHidTest V2.0 and Dll  ( 32 Bit )  ( Operates on both 32 and 64-bit computers)

ADUHidTest V2.0 and Dll  ( 64 Bit )  ( Use this one only if developing 64-bit applications.)

An AduHidTest tutorial is available in our programming section, or by clicking HERE.

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