HW definitions

Hardware definitions specify the communication with Modbus devices. They are located in /etc/evok/hw_definitions/, each file represents one Modbus device. The file name is the device code, which may be used to add the device in the Evok configuration. The file is divided into two main parts, modbus_register_blocks defines which registers will be used and how often will be read, modbus_features breaks them into individual devices.

modbus_register_blocks

Contains a list that defines the Modbus register groups. These registers must be placed consecutively. Each block is read in a separate request. Parameters:

• start_reg - first Modbus register address of the block
• count - number of Modbus registers to read
• frequency - denominator of the scanning frequency. The block will be read each scan_frequency÷frequency seconds (division).
• type - Modbus register type, set to holding (default) or input

Example

# This key defines which Modbus registers will be periodically read. Each block (also sometimes referred to as "group") is read once every ["frequency"] read cycles.
modbus_register_blocks:
    - start_reg   : 0
      count       : 10
      frequency   : 1

    - start_reg   : 500
      count       : 8
      frequency   : 10

    - start_reg   : 508
      count       : 8
      frequency   : 50
      type        : input

modbus_features

Contains a list that defines devices and their required parameters. Each element contains the following parameters:

• type - device type, supported devices are listed below.
• count - number of devices of the type, register addresses increment based on this number
• reg_type- Modbus register type, set to holding (default) or input

Other parameters depend on the specific type of device.

Note

All registers addresses are just the starting ones, they get incremented depending on the type.

DO (digital output)

Allows you to add a digital output for the Modbus device.

• val_reg - value register address, each bit will be treated as a separate device
• pwm_reg - PWM duty register address
• pwm_ps_reg - PWM prescale register address
• pwm_c_reg - PWM cycle register address
• modes - list of available DO modes
  • Simple - basic binary mode
  • PWM - output with PWM support

Tip

More information about PWM can be found on Unipi KB.

Example

  - type        : DO
    count       : 4
    modes       :
      - Simple
      - PWM
    val_reg     : 1
    val_coil    : 0
    pwm_reg     : 16
    pwm_ps_reg  : 1017
    pwm_c_reg   : 1018

RO (relay output)

Allows you to add a relay output for the Modbus device.

• val_coil - coil register address
• val_reg - value register address, each bit will be treated as a separate device

Example

  - type        : RO
    count       : 5
    val_reg     : 1
    val_coil    : 0

DI (digital input)

Allows you to add a digital input for the Modbus device.

• val_reg - value register address, each bit will be treated as a different device
• counter_reg - counter register address, two registers are used for each device
• deboun_reg - debounce register address
• modes- list of available DI modes
  • Simple - regular mode
  • DirectSwitch - DI switches RO directly in firmware
• ds_modes - list of available direct switch modes
  • Simple
  • Inverted
  • Toggle
• direct_reg - direct switch register address
• polar_reg - polarity register address
• toggle_reg - toggle register address

Example

  - type        : DI
    count       : 4
    modes       :
      - Simple
      - DirectSwitch
    ds_modes    :
      - Simple
      - Inverted
      - Toggle
    val_reg     : 0
    counter_reg : 16
    direct_reg  : 1016
    deboun_reg  : 1010
    polar_reg   : 1017
    toggle_reg  : 1018

AO (analog output)

Allows you to add an analog output for the Modbus device.

• val_reg - value register address
• mode_reg - mode register address
• modes - list of available modes (names will be available in API), each has to have specified all parameters
  • value - value for mode_reg
  • unit - value unit
  • range - min and max values defined in an array

Example

  - type        : AO
    count       : 4
    modes       :
      Voltage:
        unit: 'V'
        range: [0, 10]
    min_v       : 0
    max_v       : 10
    val_reg     : 2

AI (analog input)

Allows you to add an analog input for the Modbus device.

• val_reg - value register address
• mode_reg - mode register address
• modes - list of available modes (names will be available in API), each has to have specified all parameters
  • value - value for mode_reg
  • unit - value unit
  • range - min and max values defined in an array

Example

- type        : AI
  count       : 4
  val_reg     : 6
  mode_reg    : 1019
  modes       :
    Disabled:
      value: 0
    Voltage10:
      value: 1
      unit: 'V'
      range: [0, 10]
    Voltage2V5:
      value: 2
      unit: 'V'
      range: [0, 2.5]
    Current20m:
      value: 3
      unit: 'mA'
      range: [0, 20]
    Resistance3W:
      value: 4
      unit: 'Ohm'
      range: [0, 1960]
    Resistance2W:
      value: 5
      unit: 'Ohm'
      range: [0, 100000]

WD (watchdog)

Allows you to add a watchdog for the Modbus device.

• val_reg - value register address
• timeout_reg - timeout register address
• nv_save_coil - NV save coil address
• reset_coil - reset coil address

Example

  - type        : WD
    count       : 1
    val_reg     : 6
    timeout_reg : 1008
    nv_sav_coil : 1003
    reset_coil  : 1002

DATA_POINT (data point)

If no other type is viable, data point may be used.

• name - value name
• unit - value unit
• value_reg - value register address
• datatype - value data type
  • null
  • float32

Example

- type        : DATA_POINT
  name        : "temperature"
  count       : 1
  value_reg   : 0
  unit        : "°C"
  datatype    : float32