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Modbus Scale Low = Scale Low - (Modbus ΔScale Range - ΔScale Range)
= 500 - (600 -500) = 500 -100 = 400
Modbus Scale High = Scale High + (Modbus ΔScale Range -ΔScale Range)
= 1000 + (600 - 500) = 1000 + 100 = 1100
Convert the Modbus Scale Low value to DWord value:
(((400 * DP Value) - (-2147483648)) / (2147483647-(-2147483648))) * 4294967295
The DP Value is 1 when the DP is 0 =>
Convert the Modbus Scale High value to DWord value:
(((1100 * DP Value) - (-2147483648)) / (2147483647- (-2147483648))) * 294967295
The DP Value is 1 when the DP is 0 =>
Convert DWord value to Real Scale Value:
Modbus Scale High = ((((DWord Value - 0) * 4294967295) / 4294967295) + (-2147483648)) / DP Value
Modbus Scale Low = ((((DWord Value - 0) * 4294967295) / 4294967295) + (-2147483648)) / DP Value
= ((((2147484048-0) * 4294967295) / 4294967295) + (-2147483648))/1
= (((2147484048* 4294967295) / 4294967295) -2147483648)/1
=2147484048-2147483648
=400
8.1.3.3.2 How to calculate Scale Low / High
Let's say Scale Low is 'A' and Scale High is 'B'.
Modbus Scale Low = Scale Low - (Modbus ΔScale Range - ΔScale Range)
= Scale Low-(Scale High-Scale Low) *1.2- (Scale High-Scale Low)
=A-(B-A) *1.2-(B-A)
=A-(1.2B-1.2A-B+A)
=A-(0.2B-0.2A)
Modbus Scale Low =1.2A-0.2B-----------------------------------Equation 1
Modbus Scale High = Scale High + (Modbus ΔScale Range -ΔScale Range)
= Scale High + ((Scale High-Scale Low) *1.2 – (Scale High- Scale Low))
=B+((B-A) *1.2-(B-A))
=B+(1.2B-1.2A-B+A)
=B+(0.2B-0.2A)
Modbus Scale High =1.2B-0.2A--------------------------------- Equation 2
Multiply by 6
6*Modbus Scale High =7.2B-1.2A
1.2A=7.2B-(6*Modbus Scale High) ------------------------------Equation 3
Replace 1.2A in Equation 1 with the value in Equation 3
Modbus Scale Low =1.2A-0.2B
Modbus Scale Low=7.2B-(6*Modbus Scale High)-0.2B
Modbus Scale Low=7B-(6*Modbus Scale High)
Modbus Scale Low+(6*Modbus Scale High) =7B
(Modbus Scale Low+(6*Modbus Scale High))/7 =B--------------------------Equation 4
((400 - (-2147483648)) / 4294967295) *4294967295
= (2147484048/4294967295)* 4294967295
= 2147484048
(1100 - (-2147483648)) / (2147483647 - (-2147483648)) *4294967295
= (2147484748/4294967295)* 4294967295
=2147484748
=((((2147484748-0)* 4294967295) / 4294967295) + (-2147483648))/1
=(((2147484748*4294967295)/ 4294967295)- 2147483648)/1
=2147484748-2147483648
=1100
Page 464 of 479
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