IA-400D vs ETH-256

 VS
The IA-400D is the optimal solution for most recording requirements. It  is a 4 Channel  general purpose recorder designed for measuring signals from transducers as well as Biopotentials using the C-ISO-256 The ETH-256 is a 2 channel amplifier with selectable gain and filters, for measuring  signals from transducers as well as biopotentials. For isolated signals, such as human biopotentials, the C-ISO-256 is required.
An amplifier is used to set the Gain and Filter for a sensor.

Gain

Transducers typically require a fixed gain.  All iWorx transducers set the IA-400D gain to the optimal value for a given measurement. A programming resistor in the DIN-8 connector can be used to set the gain for non-iWorx transducers. In the unlikely situation where the signal being recorded can vary significantly in amplitude and the recorder does not have the resolution to resolve small signal. The variable gain control in the ETH-256 may be necessary.

Filter

The IA-400D has built-in 40Hz and 10KHz filter.  This allows for the recording of all DC signals such as pressure, force, temperature etc.. In addition the C-ISO-256 has High Pass Filter of 0.05 Hz and a low pass filter 25 Hz or 2500 Hz, enabling the recording of most biopotentials such as ECG and EMG. The ETH-256 has more options for high pass and low pass filters. For filter requirements not covered by the IA-400D, the ETH-256 will be a suitable amplifier.

Summary

For most applications the IA-400D is a good choice, and a more cost effective solution. It is 4 channel device and has the gain and filter setting required for most common applications. For some applications that require more gain and filter control the ETH-256 amplifier may be required.