UMAX180800, 20 Thermocouple, 2 RTD, 4 Inputs, 6 Relays Dual CAN Controller
Version 1
Page: 22-71
3.4.3 Thermocouple Input Warning and Shutdown
The temperature levels at which the Shutdown and Warning messages are triggered are
configurable. The
High Shutdown Temperature
and
Low Shutdown Temperature
parameters are used to set the upper and lower bound for when a Shutdown Diagnostic
message is sent. The
High Warning Temperature
and
Low Warning Temperature
parameters are used to set the upper and lower bound for when a Warning Diagnostic
message is sent.
The
Shutdown Delay
and
Warning Delay
parameters are used to set the delay between the
trigger and actual output of a diagnostic message. These parameters are directly linked to the
Delay Before Sending DM1
setpoint for their respective diagnostic block.
3.5 RTD Input Function Block
The RTD Input Function Block reads analog signal from two RTD sensor inputs and process
them into the temperature data.
The user can specify the type of sensor connection (2-wire or 3-wire) and approximation
parameters for each individual sensor connected to the unit using setpoint parameters.
Axiomatic EA software is used for this purpose. The setpoint parameters are kept in a non-
volatile memory of the RTD unit and are automatically loaded on power-up.
Although the diagnostics check the temperature data, the ECU is capable of providing the
output data in Ohms as well as a raw hexadecimal data that has been read from a RTD chip.
The AX180800 supports the PT100 sensor type in both 2- and 3-wire configuration. The
supported sensor connections are shown in the table below
Table 15 The Types of RTD Connections
Value
Description
0
RTD Disabled
1
Two Wires
2
Three Wires
3.5.1 RTD Coefficients
The customer can set the specific coefficients within ranges. By default the values for
Callendar - Van Dusen Coefficient A, B, and C are standard (IEC 0.00385), and can be seen
on the table below.
Table 16 The Default Value of Coefficients
Name
Default Value
Range
Units
Description
Callendar
– Van
Dusen coefficient A
3.908300
-100
…100
–
Callendar
– Van Dusen
coefficient A for the
selected standard
