Publication 1746-UM022B-EN-P - January 2005
Programming Examples 5-7
calibration time to ensure that the new input data matches the channel
configuration requested. The above table shows how to calculate the
update time and auto-calibration time for the channel configuration
being used.
Interfacing to the PID
Instruction
The thermocouple module was designed to interface directly to the
SLC 5/02 or later processor PID instruction without the need for an
intermediate scale operation.
Example - Use 1746-NT8 channel data as the process variable in the
PID instruction.
1. Select scaled-for-PID as the data type in the channel
configuration word.
2. Specify the thermocouple channel data word as the process
variable for the PID instruction.
In this example, the value -32701 (8043 H) is the numeric equivalent
of configuration word N10:0 for channel 0. It is configured for a type
K thermocouple, scaled-for-PID, zero the signal for an open-circuit,
10 Hz, °C, and channel enabled.
Programming for PID Control Example
MOV
MOVE
Source N10:0
-32701
Dest O:3.0
0
s:1
] [
15
PID
PID
Control Block N11:0
Process Variable I:3.0
Control Variable N11:23
Control Block Length 23
SCL
SCALE
Source N11:23
Rate [/10000]
Offset
Dest
First Pass Bit
Initialize NT8
Channel 0
Rung 2:0
Rung 2:1
Rung 2:2
The Rate and Offset parameters should be set per your application.
The Destination will typically be an analog output channel.
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