ET-16AI2 Usage Tips

Choice of Update (Integration) Time

EtherTRAK (-xAI2) analog inputs sample all analog input channels in an interlaced scan and integrate the results to eliminate the effects of noise. In the Windows setup software, you are given a choice of integration time. The slowest setting integrates for 100 ms, which is an integral number of power line cycles (5 cycles at 50 Hz and 6 cycles at 60 Hz). Since all channels are interlaced, a complete scan of all channels occurs in this time. Faster times may be selected, though a sacrifice of noise rejection may result.

Field Replaceable Current Shunt

Each 4-20 mA input channel has a 100 ohm precision shunt across its input to develop a 2-volt signal when a full scale 20 mA signal is applied. This shunt is in the module’s base, giving you the advantage of maintaining a continuous circuit, even if the module is removed from the base. If excessive voltage is applied to an input, this shunt will blow like a fuse to protect the measurement circuitry. These shunts are installed in sockets to allow easy field replacement. A spare shunt is provided for your convenience. These shunts are precision devices that should only be replaced with authorized factory replacements.

Open Loop Detection

This module can detect and report an open instrumentation loop on each input. By allowing the module to report a negative value if the current falls below 4 mA, low limit logic in your DCS, PLC, RTU or computer can signal the loss of current. To enable this feature, select the "Go Negative Below 4 mA" setting for each individual channel.