Vibro-Meter I/O interface card XIO16T

I/O interface card  XIO16T

Sensor signal conditioning

This block (see Figure5-2) acts as a signal interface and is used to:

• Acquire a signal from the connected sensor.

• Check for signal overload (independently of the OK line check).

The AMC8 card does not have the ability to power external measuring devices. Where

necessary, an external power supply must be used.

See 5.3Inputs and outputs.

5.2.2Signal routing

This block (see Figure5-2) is used only if cold-junction compensation (CJC) is required for

channels having a thermocouple connected.

The block enables a “cold junction” (CJ) temperature signal (generally obtained using an

RTD) to be routed to another channel on the card. One of two remote CJ signals can also be

selected. These come from other cards in the rack over Tacho Bus lines 7 and 8.

5.2.3Signal processing and monitoring

This block (see Figure5-2) assures the following:

1-Definition of “multi-channels”

Based on the eight single channels, four “multi-channels” can be defined. These can

group between two and eight single channels and perform various mathematical

operations on them, such as obtain the minimum, maximum or average value. The

difference between two individual channels can also be calculated.

See 5.4Multi-channel processing functions.

2-Selection of the time-domain processing function

The functions include the following: direct output (bypass), average over a period of time,

maximum value over a period of time, minimum value over a period of time.

See 5.5Time-domain processing functions.

3-Linearity compensation

Linear and non-linear sensor compensation can be applied for thermocouples and RTD

devices.

See 5.6Linearity compensation.

4-Monitoring

For single channels and “multi-channels”, the signal values (suitably processed and

compensated) are monitored and alarms generated if the thresholds are exceeded.

These alarms can be used to set relays.

Logical combinations of alarms can also be configured.

See 5.8Alarm monitoring.

5-Sensor OK Level Detection

This function monitors the OK levels for the sensor to check for hardware problems (for

example, faulty sensor or signal conditioner, or defective transmission line).

See 5.9System self-checks

Multi-channel processing functions

Four “multi-channel” processing functions are available. Each is able to process the following

functions on the 8 single channels:

• Minimum of 2 to 8 values

• Maximum of 2 to 8 values

• Average of 2 to 8 values

• Difference between two values.

5.5 Time-domain processing functions

These functions are somewhat analogous to the rectifier functions available for the

MPC4/ IOC4T card pair.

A time-domain processing function can be applied to a single channel or a “multi-channel”.

The following possibilities exist:

• Direct output (bypass)

• Average over a period of time

• Maximum value over a period of time

• Minimum value over a period of time.

The time period can be set under software control to a value between 0.1and10.0seconds.

The output is updated at this rate.

5.6 Linearity compensation

The VM600 MPSx software allows linearity compensation for thermocouples and RTD

devices.

For linear compensation, an offset and sensitivity value can be defined.

For non-linear compensation, a table of polynomial values can be entered or downloaded