Function description
Operating Manual PSSu E S 2AI I se(-T)
21417-EN-04
19
– Limit value 2
– The module compares limit value 1 and limit value 2 with the digital value after scal-
ing (values with 15 bits plus sign) and writes the result of the comparison as follows:
– System environment A:
– In the status byte (see "PSSu assignment in system environment A")
– System environment B:
– In the I/O data element "LimitValue1" or "LimitValue2" (see "PSSu assignment in
system environment B").
– The limit of the measuring range corresponds to 32 767
D
with default scaling val-
ues.
You can change the default values in the system software.
The decimal value for the PSSuniversal Configurator (n) is calculated from the analogue
value at the input (I
Limit
) as follows:
}
Current range 0 … 20 mA:
n = 32 768 * I
Limit
/ 20 mA
}
Current range 4 … 20 mA:
n = 32 768 * (I
Limit
– 4 mA) / 16 mA
Example:
}
Current at the input, which is to be monitored through the limit values:
– Limit value 1 is to be 8 mA.
– Limit value 2 is to be 15 mA.
}
Entry in the PSSuniversal Configurator at
Current range 0 … 20 mA:
– Limit value 1 corresponds to 13 107
– Limit value 2 corresponds to 24 576
}
Entry in the PSSuniversal Configurator at
Current range 4 … 20 mA:
– Limit value 1 corresponds to 8 192
– Limit value 2 corresponds to 22 528
4.3.4
Data formats
The way in which the analogue value is displayed depends on the voltage range, on scaling
and on the data format. The following examples show the relationship between the values
with default scaling.
The module uses the following data format:
}
Two's complement
The digital values are transferred with 15 bits plus a sign bit (MSB). The MSB is always
"0" with positive numbers.
