Sensoray 7429 - Manual (Page 14)

ALARM interrupt E19 enables alarm interrupt
System interrupt enable E18 routes interrupt request to STD bus
H ARDWARE F ILTERS
Each channel is provided with a hardware filter which may be used to filter noise from
the sensor signal. This feature is in addition to the software filter algorithm.
Sometimes it is desirable to filter a differential input signal to roll off high frequency
noise. For example, thermocouple wires might be pulled alongside high current cables
capable of coupling noise onto the thermocouple. This noise can often be reduced by
inserting the channel hardware filter into the input circuit of the corresponding thermo-
couple channel.
In other cases, however, hardware filtering produces undesireable side effects. For ex-
ample, RTD's and thermistors are powered by a pulsed current source. Filtering signals
from these sensors can result in inaccurate measurements.
Jumpers E1 through E16 are used to connect hardware filters to channels 0 through 15,
respectively. Install the appropriate shunt to connect a channel hardware filter, or re-
move the shunt to disconnect the filter.
Sensoray recommends the following configurations for the varied sensors supported by
the 7429:
Sensor Type Filter
Thermocouples Installed
Direct voltage Installed
Strain gages Removed
Thermistors Removed
RTD's Removed
4-20 mA source Removed