Modbus master controller

Contents

Modbus master controller
- Setup
- EAPI methods
  - action
  - kill
  - reg.get
  - reg.set
  - terminate

Allows to communicate with Modbus-powered PLCs and other equipment.

Setup

Use the template EVA_DIR/share/svc-tpl/svc-tpl-controller-modbus.yml:

# Modbus master controller service
command: svc/eva-controller-modbus
bus:
  path: var/bus.ipc
config:
  modbus: 
    protocol: tcp # udp, rtu, ascii or native for the local bus
    path: 192.168.1.200:502 # for serial:
    #  /dev/ttySXX:SPEED:DATABITS:PARITY:STOPBITS, e.g. /dev/ttyS0:9600:8:N:1
    #  for the local bus: service name
    unit: 1 # default modbus unit
    # frame_delay: 0.1 # optional serial frame delay (sec), default: 0.1 (100ms)
    # set to false if the target device is unable to process FC16 (bulk set,
    # default: true)
    #fc16_supported: false
    # turn off TCP keep-alive (opens a new connection per request), can be used
    # for devices which can not handle Modbus command queue properly (SLOW!)
    #keep_alive: false
  # panic on critical errors in X seconds after happened (0 - panic immediately)
  panic_in: null
  # default retry attempts for all operations (0 - no retries, give up if the
  # first attempt fails)
  retries: 2
  # an optional delay betwen writing tags and verifying written value
  #verify_delay: 0.1
  # event queue size, pull events ARE DROPPED on overflow. consider ALWAYS
  # having queue size > max possible tags pulled
  queue_size: 32768
  # ttl cache for pull events (sec, skip non-modified)
  pull_cache_sec: 3600
  # PLC pull interval, in seconds
  pull_interval: 1
  # pull blocks and parse maps
  #
  # the configuration is very similar (but extended) to the widely-used
  # https://github.com/alttch/pulr tool
  #
  #pull:
    #- reg: h0 # h = holding, i = input, d = discrete, c = coils
      #count: 10
      #unit: 1 # override the default modbus unit
      #map:
        #- offset: 0
          #  Offsets ARE NOT register numbers, but absolute offsets in block
          #  can be written as N+N+N
          ## absoltue offset (reg no.) can be specified as =N
          #oid: sensor:tests/test0
          # allowed types: real (REAL), real32, real64 (LREAL), real32b,
          # real64b (for IEEE 754 big-endian), uint16 (UINT), word, uint32
          # (UDINT), dword, sint16 (INT), int16, sint32 (DINT),
          # int32, sint64 (LINT), int64, uint64 (ULINT), qword
          # float numbers are decoded/encoded as IEEE754
          #type: real
        #- offset: 0+4
          #oid: sensor:tests/test1
          #type: real
          #value_delta: 0.5 # report event only if the new value difference is >=
          #transform:
            #- func: multiply # multiply the value by N
              #params: [ 1000 ]
            #- func: divide # divide the value by N
              #params: [ 1000 ]
            #- func: round # round the value to N digits after comma
              #params: [ 2 ]
            #- func: calc_speed # use the value as calc-speed gauge (with N seconds delta)
              #params: [ 1 ]
            #- func: invert # invert the value between 0/1
            # #params: []
    # pull bits
    #- reg: h100
      #count: 1
      #unit: 1 # override the default modbus unit
      #map:
        #- offset: 0/0
          #oid: sensor:tests/flag0
        #- offset: 0/1
          #oid: unit:tests/u1
    # pull coils
    #- reg: c0
      #count: 2
      #unit: 1 # override the default modbus unit
      #map:
        #- offset: 0
          # pull coil as unit value   
          #oid: unit:tests/relay_1
        #- offset: 1
          #oid: unit:tests/relay_2
  # action queue size, per item, actions on overflow are not dropped but wait
  # their attempt to enter the queue. The core marks an action as failed if it
  # does not enter the queue for <action timeout> seconds
  action_queue_size: 32
  # verify written data for actions
  actions_verify: true
  # OID map for actions
  #action_map:
    #unit:tests/u1:
      #reg: h100
      #type: real
      #unit: 1 # override the default modbus unit
    #unit:tests/u3:
      #reg: c10
timeout:
  # startup timeout should be slightly langer than default to allow the
  # controller prepare connection pool
  startup: 10
user: nobody
react_to_fail: true

Create the service using eva-shell:

eva svc create eva.controller.modbus1 /opt/eva4/share/svc-tpl/svc-tpl-controller-modbus.yml

or using the bus CLI client:

cd /opt/eva4
cat DEPLOY.yml | ./bin/yml2mp | \
    ./sbin/bus ./var/bus.ipc rpc call eva.core svc.deploy -

(see eva.core::svc.deploy for more info)

EAPI methods

See EAPI commons for the common information about the bus, types, errors and RPC calls.

action

Description	Executes a mapped unit action
Parameters	See Unit actions
Returns	See Unit actions

kill

Description	Attempts to terinate/cancel all actions for a unit
Parameters	See Unit actions
Returns	See Unit actions

reg.get

Description	Get Modbus slave register
Parameters	required
Returns	Tag value, single or list

Parameters
Name	Type	Description	Required
unit	u8	Modbus unit ID	yes
reg	String	Register (h/i/d/c e.g. h100 for holding #100)	yes
type	String	Data type (e.g. DINT)	no
bit	u8	Get an individual bit	no
count	u32	Count of bits/registers	no
timeout	f64	Max operation timeout	no
retries	u8	Retry attempts	no

reg.set

Description	Set Modbus slave register
Parameters	required
Returns	nothing

Parameters
Name	Type	Description	Required
unit	u8	Modbus unit ID	yes
reg	String	Register (h/i/d/c e.g. h100 for holding #100)	yes
value	Any	value to set	yes
type	String	Data type (e.g. DINT)	no
bit	u8	Get an individual bit	no
verify	bool	Read the register back and verify its value	no
timeout	f64	Max operation timeout	no
retries	u8	Retry attempts	no

terminate

Description	Attempts to terminate/cancel a unit action
Parameters	See Unit actions
Returns	See Unit actions