RM-16AI2-H Usage Tips

This high density 4-20 mA input module provides the lowest cost per point solution for locations with more than eight input channels. Since only one terminal is provided per input, it is necessary to provide return wiring connections (power or ground) external to the module.

Field Replaceable Current Shunts

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) input is applied. This shunt is located 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 circuit. 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 its 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.

Input Update Time

These 16 bit precision analog inputs integrate the signal using advanced signal correlation techniques. Superior noise rejection results from this integration, which takes approximately 50 mS per channel. Unused channels may be disabled in the Analog Channel Definition Window by selecting the feature "Disable Channel". Disabled channels are not scanned, speeding up the polling of the remaining channels. It should be noted that eight channel input modules scan all inputs at a rate slightly faster than the high density module.