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ADP102 Isolated DIO module

The OnLogic ADP102 provides isolated digital inputs and outputs for safe external signal control. The adapter USB interface and wide input voltage range offer enhanced versatility. The onboard ARM processor allows for fast, reliable operation independent of host system.


  • Isolated Digital Input/Output
  • Four Inputs, 0-16V (2.5V HIGH), dry contact 
  • Four Outputs, 50mA, open collector 
  • Keyed 2.54mm connector 
  • IO Isolation to 3750 Volts (​*Rated, not tested​) 
  • Simple-to-program USB-serial interface 
  • Onboard ARM Cortex-M0 processor
  • Latches and 32-bit counters for inputs 

Connections & Wiring 

DIO Header (externally facing)

USB J1 (Left) MISC J2 (Right)

Sample Input Circuit

Digital inputs are triggered by the flow of a small amount (1-2mA) of current through DI. Current is limited, and  correct polarity is ensured by the ADP102’s built-in protection circuit. A request for DI state will report active  when the voltage at DI exceeds 2.5 V. 

Sample Output Circuit 

Digital outputs switch a circuit in series after the device they control (represented by LOAD). Each output is  rated for 50mA. If more than 50mA are required, DO may be used to trigger a relay driving LOAD instead. 

Application Interface 

The ADP102 provides a standard USB-CDC (USB-serial) interface. To determine the COM port number, check device manager or equivalent for the COM device. A developer may employ any  serial-compatible software library in order to communicate with the ADP102.  Available commands are outlined below. After the execution of any command, a response is returned by the  ADP102 containing any requested data. For commands that do not return a value, a success/failure code is  returned instead. 

Command Structure 

Each command is comprised of a start character, length (not including the start character), 1-byte pin address,  2-byte command ID, and (optional) data.  For example, to set the state of digital output 3 to ‘ON’, the command packet is: 

StartLengthAddressCommand HighCommand  Low Data
0x24 0x05 0x030x010x020xFF

Digital Output Commands 

Get State  0x0101AddressGet the IO pin input state. Returns the status of output pins as well.
Get Latch State0x0102AddressGet the input pin latch bit state.
Get Count0x0103AddressGet the input pin counter value. This counter is  incremented at every low-to-high or high-to-low  state change, depending on configuration.
Clear Count 0x0104AddressReturn the input counter value, then reset it to  zero. 
Set State0x0108Address, StateSet an output pin to the specified state. 0x00  species LOW, all others evaluate to HIGH. 
Toggle State 0x0109AddressToggle an output pin to the opposite state.
Get Model Number0x0001NoneReturn the device model number.
Get Firmware  Version 0x0002NoneGet device firmware revision.
Get Configuration0x0004AddressReturn the configuration of the specified pin. 
Set Configuration0x0005Address,  Configuration Set the configuration of the specified pin.  Available configuration settings are described in  the section below. Unless this is followed by  “Save Configuration” this is not preserved across  reboots. 
Save Configuration0x00060x00Save all pin configurations as “boot” settings.  0x00 must be provided in the data field. 

Response Structure 

 After executing each command, the ADP102 issues a response containing data the command generated (if any)  and a success code.   The first two bytes of a response packet are the incoming command code that generated the response OR’d  with 0x8000, followed by the pin number requested and any relevant data. The packet is completed by the  same carriage return delimiter as the command packet. 

 For example, a response to the ‘Get input status’ command looks like this: 

Start Byte LengthAddressCommand HighCommand  LowDataEnd 

State Change Reports 

The ADP102 may also be configured to send a report to the host system whenever an input changes state, or a  counter overflows (reaches the maximum value of 2^32 and resets). These reports are formatted as responses  to the input “Get State” command (​0x8101 [Address] [State] 0x13​). They may be enabled or disabled via their  respective configuration bits in each pin’s configuration. 

Updated on June 19, 2020

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