# Slot 3 Menu 15 − Modbus

Mode: RFC‑A

Parameter | 3.15.001 Enable Modbus
--- | ---
Short description | Set to enable Modbus functionality
Minimum | 0 | Maximum | 1
Default | 1 | Units |
Type | 1 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 0
Coding | RW, BU

This parameter is used to enable or disable Modbus master and slave functionality.

Parameter | 3.15.002 Reset Modbus
--- | ---
Short description | Set to reset the interface
Minimum | 0 | Maximum | 1
Default | 0 | Units |
Type | 1 Bit Volatile | Update Rate | Background read; written to 0 on initialisation
Display Format | Standard | Decimal Places | 0
Coding | RW, NC

This parameter is used to perform a warm reset of the protocol interface. When set and the protocol has reset, the parameter will be reset to zero (Off).

Parameter | 3.15.003 Default Modbus
--- | ---
Short description | Set to default the protocol interface
Minimum | 0 | Maximum | 1
Default | 0 | Units |
Type | 1 Bit Volatile | Update Rate | On module reset, protocol interface reset or protocol enable
Display Format | Standard | Decimal Places | 0
Coding | RW, NC

This parameter allows the protocol to be defaulted to factory settings. This includes all of the protocol features, configuration, mappings and stored objects.

Parameter | 3.15.004 Modbus Configuration Error
--- | ---
Short description | Displays the Modbus configuration error
Minimum | 0 | Maximum | 4
Default |  | Units |
Type | 8 Bit Volatile | Update Rate | Module reset, Modbus interface reset or Modbus interface enable
Display Format | Standard | Decimal Places | 0
Coding | RO, TE, ND, NC, PT, BU

Value | Text | Description
0 | No error | No error
1 | Port in use | Specified port is currently in use by another protocol
2 | Timeout event | Timeout trigger event location is not valid
3 | Out of memory | Out of memory
4 | Connection error | Max connection is less than Priority connection

This parameter will indicate any Modbus configuration errors.

Parameter | 3.15.005 Modbus Listening Port
--- | ---
Short description | Defines the Modbus TCP/IP port
Minimum | 0 | Maximum | 65535
Default | 502 | Units |
Type | 16 Bit User Save | Update Rate | MODBUS_THREAD_TICK_TIME
Display Format | Standard | Decimal Places | 0
Coding | RW, BU

This parameter can be changed from its default port of 502, however it is the user's responsibility to ensure that a valid port is set.

Parameter | 3.15.006 Maximum Connections
--- | ---
Short description | Defines the maximum number of connections to the module
Minimum | 0 | Maximum | 4
Default | 3 | Units |
Type | 8 Bit User Save | Update Rate | Module reset, Modbus interface reset or Modbus interface enable
Display Format | Standard | Decimal Places | 0
Coding | RW, BU

This parameter permits the user to specify the total number of connections that one or more clients can open with the module at any one time.

Parameter | 3.15.007 Maximum Priority Connections
--- | ---
Short description | Defines the maximum number of priority connections
Minimum | 0 | Maximum | 4
Default | 0 | Units |
Type | 8 Bit User Save | Update Rate | Module reset, Modbus interface reset or Modbus interface enable
Display Format | Standard | Decimal Places | 0
Coding | RW, BU

This parameter defines the how many of the maximum connections specified in Maximum Connections (3.15.006) can be configured as a priority connection. A connection is accepted into the priority connections pool if the client's IP address matches one of the values stored in parameters Priority Connection 1 (3.15.020), Priority Connection 2 (3.15.021), Priority Connection 3 (3.15.022) or Priority Connection 4 (3.15.023).

The priority connections are permanent and, once made will only be deleted at the request of the client or due to a communications error.

Any connections not in the priority connections pool are kept in the non-priority connections pool. If a client attempts to establish a priority connection and all available non-priority connections are in use, the non-priority connection that has not been used for the longest will be closed to make way for the new priority connection.

Parameter | 3.15.008 Maximum Connections Per Client
--- | ---
Short description | Defines the maximum number of connections per client
Minimum | 1 | Maximum | 4
Default | 2 | Units |
Type | 8 Bit User Save | Update Rate | Module reset, Modbus interface reset or Modbus interface enable
Display Format | Standard | Decimal Places | 0
Coding | RW, BU

This parameter defines the maximum number of connections that any one client can establish. This check is only performed on the connections in the priority connections pool.

Parameter | 3.15.009 Modbus Timeout
--- | ---
Short description | Defines the Modbus timeout value
Minimum | 1 | Maximum | 10000
Default | 100 | Units | ms
Type | 16 Bit User Save | Update Rate | Module reset, Modbus interface reset or Modbus interface enable
Display Format | Standard | Decimal Places | 0
Coding | RW, BU

This parameter defines the time period in which the Modbus server must receive a message before any specified action (as defined in ) is performed. When the timeout occurs, bit 1 in the module's alarm parameter () will be set and the specified action will be performed.

The timeout is enabled when the server receives its first message.

Note:
It is good system design to allow for some message loss by setting the timeout duration to be greater than the transmit period by a factor of 2 or more.

Parameter | 3.15.010 Modbus Timeout Action
--- | ---
Short description | Defines the action to perform on a Modbus timeout
Minimum | 0 | Maximum | 1
Default | 1 | Units |
Type | 8 Bit User Save | Update Rate | Module reset, Modbus interface reset or Modbus interface enable
Display Format | Standard | Decimal Places | 0
Coding | RW, TE, BU

Value | Text | Description
0 | Trip | Trip drive and raise error
1 | No action | No action

Defines the action when no message is received within the time period specified in Modbus Timeout (3.15.009).

Parameter | 3.15.012 Modbus Timeout Event Type
--- | ---
Short description | Defines the event type to trigger
Minimum | 0 | Maximum | 4
Default | 0 | Units |
Type | 8 Bit User Save | Update Rate | Module reset, Modbus interface reset or Modbus interface enable
Display Format | Standard | Decimal Places | 0
Coding | RW, TE, BU

Value | Text | Description
0 | No event | No event
1 | Event 0 | Trigger module event 0
2 | Event 1 | Trigger module event 1
3 | Event 2 | Trigger module event 2
4 | Event 3 | Trigger module event 3

Defines the event to trigger when a timeout occurs. Modbus Timeout Event Destination (3.15.011) must specify an appropriate consumer (slot option) of the event.

Parameter | 3.15.013 Modbus Register Addressing Mode
--- | ---
Short description | Defines the Modbus register addressing mode
Minimum | 0 | Maximum | 1
Default | 0 | Units |
Type | 8 Bit User Save | Update Rate | Module reset, Modbus interface reset or Modbus interface enable
Display Format | Standard | Decimal Places | 0
Coding | RW, TE, BU

Value | Text | Description
0 | Standard | (mm x 100) + ppp - mm<=162 and ppp<=99
1 | Modified | (mm x 256) + ppp - mm<=63 and ppp<=255

Specifies the Modbus register addressing mode.

Parameter | 3.15.020 Priority Connection 1
--- | ---
Short description | Specifies the IP address for the connection
Minimum | 0 (Display: 0.0.0.0) | Maximum | 4294967295 (Display: 255.255.255.255)
Default | 0 (Display: 0.0.0.0) | Units |
Type | 32 Bit User Save | Update Rate | Module reset, Modbus interface reset or Modbus interface enable
Display Format | IP Address | Decimal Places | 0
Coding | RW, BU

This parameter specifies an IP address for a priority connection.

Parameter | 3.15.021 Priority Connection 2
--- | ---
Short description | Specifies the IP address for the connection
Minimum | 0 (Display: 0.0.0.0) | Maximum | 4294967295 (Display: 255.255.255.255)
Default | 0 (Display: 0.0.0.0) | Units |
Type | 32 Bit User Save | Update Rate | Module reset, Modbus interface reset or Modbus interface enable
Display Format | IP Address | Decimal Places | 0
Coding | RW, BU

This parameter specifies an IP address for a priority connection.

Parameter | 3.15.022 Priority Connection 3
--- | ---
Short description | Specifies the IP address for the connection
Minimum | 0 (Display: 0.0.0.0) | Maximum | 4294967295 (Display: 255.255.255.255)
Default | 0 (Display: 0.0.0.0) | Units |
Type | 32 Bit User Save | Update Rate | Module reset, Modbus interface reset or Modbus interface enable
Display Format | IP Address | Decimal Places | 0
Coding | RW, BU

This parameter specifies an IP address for a priority connection.

Parameter | 3.15.023 Priority Connection 4
--- | ---
Short description | Specifies the IP address for the connection
Minimum | 0 (Display: 0.0.0.0) | Maximum | 4294967295 (Display: 255.255.255.255)
Default | 0 (Display: 0.0.0.0) | Units |
Type | 32 Bit User Save | Update Rate | Module reset, Modbus interface reset or Modbus interface enable
Display Format | IP Address | Decimal Places | 0
Coding | RW, BU

This parameter specifies an IP address for a priority connection.