Product Overview

Theory Of Operation

The following image shows a high level overview of the internal LXA IOBus 4DO-3DI-3AI building blocks:

                        ╭───────────────────────╮
                        │ LXA IOBus 4DO-3DI-3AI │
          ╭─────────────┴───────────────────────┴─────────────╮
          │                                     ╭───────╮     │
          │                                     │Solid ┏┿━━━━━┿━╾
          │           ┏━━━━━━━━━━━━━━━━━━━━━━━━>│state ┇│     │ Out 0
          │           ┃                         │relays┗┿━━━━━┿━╾
          │           ┃                         ╰───────╯     │
          │           ┃                         ╭───────╮     │
          │           ┃                         │Solid ┏┿━━━━━┿━╾
          │           ┃ ┏━━━━━━━━━━━━━━━━━━━━━━>│state ┇│     │ Out 1
          │           ┃ ┃                       │relays┗┿━━━━━┿━╾
          │           ┃ ┃                       ╰───────╯     │
          │           ┃ ┃                       ╭───────╮     │
          │           ┃ ┃                       │Solid ┏┿━━━━━┿━╾
          │           ┃ ┃ ┏━━━━━━━━━━━━━━━━━━━━>│state ┇│     │ Out 2
          │           ┃ ┃ ┃                     │relays┗┿━━━━━┿━╾
          │           ┃ ┃ ┃                     ╰───────╯     │
          │           ┃ ┃ ┃                     ╭───────╮     │
          │           ┃ ┃ ┃                     │Solid ┏┿━━━━━┿━╾
          │           ┃ ┃ ┃ ┏━━━━━━━━━━━━━━━━━━>│state ┇│     │ Out 3
          │           A A A A                   │relays┗┿━━━━━┿━╾
          │         ╭─────────╮                 ╰───────╯     │
     CAN ╼┿━━━━━━━<>│         │<━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┿━╾ ADC in 0
 D-SUB 9  │         │  IOBus  │<━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┿━╾ ADC in 1
Connector │         │ Control │<━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┿━╾ ADC in 3
    +12V ╼┿━━━━━━━━>│         │<━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┿━╾ System GND
          │         ╰─────────╯                 ╭───────╮     │
          │            A A A                    │Solid  │<━━━━┿╾ In 0
          │            ┃ ┃ ┗━━━━━━━━━━━━━━━━━━━<│state  │     │
          │            ┃ ┃                      │relays │<━━┳━┿╾ In GND
          │            ┃ ┃                      ╰───────╯   ┃ │
          │            ┃ ┃                      ╭───────╮   ┃ │
          │            ┃ ┃                      │Solid  │<━━━━┿╾ In 1
          │            ┃ ┗━━━━━━━━━━━━━━━━━━━━━<│state  │   ┃ │
          │            ┃                        │relays │<━━╋━┿╾ In GND
          │            ┃                        ╰───────╯   ┃ │
          │            ┃                        ╭───────╮   ┃ │
          │            ┃                        │Solid  │<━━━━┿╾ In 2
          │            ┗━━━━━━━━━━━━━━━━━━━━━━━<│state  │   ┃ │
          │                                     │relays │<━━┻━┿╾ In GND
          │                                     ╰───────╯     │
          ╰───────────────────────────────────────────────────╯

The main component of the LXA IOBus 4DO-3DI-3AI are a CAN-capable microcontroller with an integrated analog to digital converter (ADC) and solid state relays providing isolation into and out of the device.

Electrical Isolation

The digital outputs and digital inputs of the LXA IOBus 4DO-3DI-3AI are galvanically isolated from the rest of the IOBus infrastructure. The ADC inputs however are not isolated from the overall system GND.

The limiting factor for the digital input/output isolation with respect to system GND is the PCB design. All input and output voltages should be kept within ±25V of system GND.

To minimize the amount of cabling required in a typical setup, the three digital input GNDs are internally connected. This is not strictly required for the operation of the device. You may disconnect the individual input GNDs by cutting the indicated traces on the back of the PCB.

IOBus Control

The device is controlled using the CANopen-inspired IOBus protocol. This protocol and wiring interface allows the usage of multiple IOBus based devices on a single bus infrastructure.