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Then the Poll Table calls POD number 12 for all the mathematical functions, and copies then copies the resulting values back to the original source unit ("SimData").
The logic contained in POD #12 is shown in the following screen capture. For each of the three data values,
- The copied value (registers 30001-30003) is ASSIGN'ed to a temporary RTDB register (such as registers 30001-3000339001-39003). The result value should be cast as integer or REAL32/floating point, or Boolean if using digital values.
- The math functions are performed (in this example, Multiply, Divide, and Add).
- Temporary holding registers (in this example, 39001-39003) or Scratchpad registers are used to hold intermediate values.
- The calculated output is assigned to a final register (40001, 40002, 44001) in the ScaledUnit database.
These final registers are copied back to the original Field Unit (SimData) by the Poll Table rows, described above.
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NOTE: Be aware that register data types will affect the calculations. For instance:
Be careful not to copy the modified values back into the same registers as the original source value – this will cause irregularities as the original value and modified value are alternately placed stored into the same register. |
This configuration gives just a few examples of how POD logic may be used to modify data in the RediGate. For illustration, it is shown as a separate channel for performing the math functions.
But for configurations that contain data already existing in an existing Internal Master unit (such as "SimData"), the new POD function could have instead been added to the existing Field Unit to modify data right in the RTDB, without requiring the registers to be copied to and from the ScaledData unit using a Poll Table.
See the POD Programming Manual for more details on using POD logic statements.
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