In this example phase currents IL1...IL3 are mapped into user-definable register addresses 0xB…0xC (11…13). Some indication bits that have been assembled into register 0xD (14), LEDPTRC1.Str.general and LEDPTRC1.Op.general, correspond to the Start/Operate LED states in the protection relay. CB1 Open, Close and Fault are all Circuit Breaker1 position data. Furthermore it is assumed that this data is mapped in Profibus offset addresses 4 and onwards.Figure 1. User definable area mappings
The SPA commands for poll in values (SPA address 10) to fetch ZC-302 Profibus octet-offset values into 4 and onwards.
>10R11I31: Read register 11 as an unsigned integer … map to Profibus offset 4...5
>10R12I31: Read register 12 as an unsigned integer … map to Profibus offset 6...7
>10R13I31: Read register 13 as an unsigned integer … map to Profibus offset 8...9
The bits in register 14 can be fetched as an integer value.
>10R14I31: Read register 14 as an unsigned integer … map to Profibus offset 10...11
Profibus offsets 4...11 values assembled sequentially are achieved more efficiently by reading two Modbus registers at a time using only two SPA polls.
>10R11I42:CC Read registers 11 and 12 as a 32-bit hex value, into Profibus offsets 4...7
>10R13I42:CC Read registers 13 and 14 as a 32-bit hex value, into Profibus offsets 8...11
The value format was changed into hex values. This creates a shorter SPA response data value which saves SPA communication bandwidth. I41 (unsigned 32 bit integer) also can be used. SPA ZC-302 accepts both of these value types.
It does not matter how the separate data values have been polled into its Profibus memory area from the SPA ZC-302 point of view. It is not necessary to poll each object in one by one. This means that the User Definable Modbus area is sequentially filled up with the Modbus values to be transferred to Profibus offset octets. Then the data can be polled into SPA ZC-302 using two register reads at a time.