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Supported Modbus formats used in Modbus Master Map module.

Issue
The supported formats used in Device Map setup register in a Modbus Master Map module.

Product Line
ION meters

Environment
ION meter template

Cause
Correct format for a register has to be specified in order for read operation to succeed.

Resolution
See the table below for supported Modbus formats:

Register Size (prefix NR)
This determines the size or number of registers that will be read and decoded. One register is 16-bit, two are 32-bit. Valid values are 1 and 2.

Scaling (prefix S)
This determines the scaling that will be applied to the Modbus values. This is used to compensate for scaling applied by the Modbus Slave device. The scaling value is divided into the Modbus value (see formula below). Valid values are +/- 1 x 106 to +/- 1 x 10-6. A scaling value of one (S1) means no scaling will be applied (Modbus value will be divided by one)

Offset (prefix O)
This determines the offset that will be applied to the Modbus values. This is used to compensate for offset applied by the Modbus Slave device. The offset value is subtracted from the Modbus value (see formula below). Valid values are +/- 1 x 106.

Offset and Scaling Applied
The following formula is applied to the value, when scaling and offset is used:

OUTPUT VALUE = (INPUT VALUE - OFFSET) / SCALING