Spectrum Controls 1769sc-IT6I - Manual (Page 39)

Chapter 4: Module, Data, Status, and Channel Configuration 4-5
User’s Manual Pub. 0300244-01 Rev. A
selected. The raw/proportional data format also provides the best resolution of all the
data formats.
If you select the raw/proportional data format for a channel, the data word will be a
number between -32767 and +32767. For example, if a type J thermocouple is selected,
the lowest temperature of -210°C corresponds to -32767 counts. The highest temperature
of 1200°C corresponds to +32767.
Engineering Units x1
When using this data format for a thermocouple or millivolt input, the module scales the
thermocouple or millivolt input data to the actual engineering values for the selected
millivolt input or thermocouple type. It expresses temperatures in 0.1°C or 0.1°F units.
For millivolt inputs, the module expresses voltages in 0.01 mV units.
Note: Use the engineering units x 10 setting to produce temperature readings in whole
degrees Celsius or Fahrenheit.
Engineering Units x10
When using a thermocouple input with this data format, the module scales the input data
to the actual temperature values for the selected thermocouple type. With this format, the
module expresses temperatures in 1°C or 1°F units. For millivolt inputs, the module
expresses voltages in 0.1 mV units.
Scaled for PID
The value presented to the controller is a signed integer with 0 representing the lower
input range and +16383 representing the upper input range.
To obtain the value, the module scales the input signal range to a 0 to +16383 range,
which is standard to the PID algorithm for the MicroLogix 1500 and other Allen-Bradley
controllers (e.g. SLC). For example, if type J thermocouple is used, the lowest
temperature for the thermocouple is -210°C, which corresponds to 0 counts. The highest
temperature in the input range, 1200°C, corresponds to +16383 counts.
Percent Range
Input data is presented to the user as a percent of the specified range. The module scales
the input signal range to a 0 to +10000 range. For example, using a type J thermocouple,
the range -210°C to +1200°C is represented as 0% to 100%.
4.2.5 Selecting Input Type (Bits 8 through 11)
Bits 8 through 11 in the channel configuration word indicate the type of thermocouple or
millivolt input device. Each channel can be individually configured for any type of input.
4.2.6 Selecting Temperature Units (Bit 7)
The module supports two different linearized/scaled ranges for thermocouples, degrees
Celsius (°C) and degrees Fahrenheit (°F). Bit 7 is ignored for millivolt input types, or
when raw/proportional, scaled-for-PID, or percent data formats are used.
If you are using engineering units x 1 data format and degrees
Fahrenheit temperature units, thermocouple types B and C cannot
achieve full-scale temperature with 16-bit signed numerical
representation. An over-range error will occur for the configured
channel if it tries to represent the full-scale value. The maximum
representable temperature is 3276.7°F.
!
Attention