User manual

Chapter 4 Configuration

Page 129 ©February 2009

When adding mappings, software will automatically adjust the available 40000 register address

range depending on the command type (i.e. read or write fieldbus mapping), see below.

The I/O Register selection below for the fieldbus read mapping illustrates the allowable 40000

The fieldbus write mapping links the 48 I/O registers 0 – 47 to the fieldbus interface 4X registers

40001 – 40048. As described earlier, fieldbus interface registers 40001 – 40032 are always

assigned as Global Data Out registers (i.e. Data To Network), these registers will be broadcast to

the network on each token rotation cycle. The remaining registers (40033 – 40048) can be

accessed via Modbus 40000 point-to-point Read Register commands described in section 4.14.3

NOTE - the option also exists for the Global Data output registers 40001 – 40032 to be read by

the point-to-point commands also.

The fieldbus read mapping links the 48 fieldbus interface registers 41025 – 41072 to the I/O

registers 50 – 97. As described earlier, fieldbus interface registers 41025 – 41056 are always

assigned as Global Data In registers (i.e. Data From Network). These registers will be filled with

Global Data broadcast by the “Source Unit” according to the “GDB I/P Offset” and “GDB I/P

Count” parameters. In the above example, the values of the Offset = 0 and Count = 32, indicating

that the entire 32 word Global Data broadcast from the Source Unit will be read into fieldbus

interface registers 41025 – 41056. Other nodes on the network can write to the remaining

registers (41057 – 41072) only by using the Modbus point-to-point Write Register commands

described in section 4.14.3. NOTE – the point-to-point Write Register commands can not be

used to write to the Global Data Input registers 41025 – 41056.