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Unit NameEnter the field unit name.
Unit name is displayed in diagnostic menus and in an HCP diagnostic screen.  
Unit AddressEnter the actual field unit address which is configured in the device being polled.
Valid Modbus addresses 1 to 255.

FieldUnit - Modbus Master (and others)

See the Elecsys documentation on various FieldUnit protocols for information on configuring the FieldUnit, including protocol-specific Poll Table, such as:


Slave Address

Enter the Modbus slave address that will respond on this slave channel
The Slave Address must be a valid Modbus address (1 to 255), and must be unique for all Slave Attach Lists on this Slave Channel. 

ReservedReserved field, currently unused. 
Source ChannelMaster Channel or Internal Channel of the Field Unit and RTDB to be attached to this Slave unit. 
Source Field Unit

Field Unit address containing the RTDB to be used as data represented in this Slave unit. 

32-bit data is only supported in 40,xxx RTDB registers, not 30,xxx registers. In order for the Modbus Slave Attach to work properly, the registers in the attached RTDB must be defined in a specific order. That order is: 

  • Booleans (should be addresses in the ranges of 1-9999 and 10,001-19,999)
  • 16-bit registers (should be addresses in the ranges of 30,001-39,999 or 40,001-49,999; there must also be at least one 16-bit holding register defined at the beginning of the 40,xxx range, before any 32-bit types)
  • UINT32 registers (should be addresses in the 40,xxx range, above the 16-bit registers)
  • FLOAT registers (should be addresses in the 40,xxx range, above the UINT32 registers) 
  • String registers are not fully supported in the Modbus Slave.

All of the above register types are optional, but must be defined in the listed order (if present) using NOTE: The RTDB attached to the Modbus slave should include at least one register in each of the four address ranges (1, 10001, 30001, 40001), observing the rules stated in the bullets above. For instance, if the RTDB definition includes 16-bit registers after UINT32 or FLOAT registers, those 16-bit registers will not work properly when attached to the Modbus Slave.