NI CFP-DI-304 Digital Input Module

NI CFP-DI-304  Digital Input Module

Features

The cFP-DI-304 is a FieldPoint digital input module with the following features:

• 32 sinking digital input channels 

• Compatible with 24 VDC sourcing-output devices 

• Inputs protected up to 30 VDC (up to 60 VDC on up to eight channels) 

• 250 Vrms CAT II continuous channel-to-ground isolation, verified by 2,300 Vrms, 5 s dielectric withstand test 

• On/off LED indicators 

• Hot swappable

Digital Input Circuitry

The cFP-DI-304 has 32 input channels. You can connect a voltage signal to each channel. All 32 input channels share a common ground reference that is isolated from other modules in the FieldPoint system.

When you apply a voltage above 10 V to a VIN terminal, current flows through that terminal and the channel is ON. When you apply a voltage below 5 V to a VIN terminal, the channel is OFF. When you apply a voltage between 5 and 10 V, the channel may be ON or OFF.

The cFP-DI-304 has sinking inputs, which means that current flows through the VIN terminal to the input circuitry. The inputs are compatible with sourcing-output devices capable of sourcing or driving current from a positive supply voltage to common. A sensor is an example of a sourcing-output device.

Make sure that devices you connect to the cFP-DI-304 have OFF state leakage currents of less than 150 µA to ensure that they do not provide false ON state readings to the cFP-DI-304.

Isolation and Safety Guidelines

This section describes the isolation of the cFP-DI-304 and its compliance with international safety standards. The field wiring connections are isolated from the backplane and the inter-module communication bus. The isolation barriers in the module provide 250 Vrms Measurement Category II continuous channel-to-backplane and channel-to-ground isolation, verified by a 2,300 Vrms, 5 s dielectric withstand test.2 The cFP-DI-304 provides double insulation compliant with IEC 61010-1 for working voltages of 250 Vrms. 3 Safety standards (such as those published by UL and IEC) require the use of double insulation between hazardous voltages and any human-accessible parts or circuits.

Never try to use any isolation product between human-accessible parts (such as DIN rails or monitoring stations) and circuits that can be at hazardous potentials under normal conditions, unless the product is specifically designed for such an application, as is the cFP-DI-304.

Even though the cFP-DI-304 is designed to handle applications with hazardous potentials, follow these guidelines to ensure a safe total system:    

• There is no isolation between channels on the cFP-DI-304. If a hazardous voltage is present on any channel, all channels are considered hazardous. Make sure that all other devices and circuits connected to the module are properly insulated from human contact. 

• Do not share the external supply voltages (the V and C terminals) with other devices, including other FieldPoint devices, unless those devices are isolated from human contact.

• For Compact FieldPoint, you must connect the protective earth (PE) ground terminal on the cFP-BP-x backplane to the system safety ground. The backplane PE ground terminal has the following symbol stamped beside it: . Connect the backplane PE ground terminal to the system safety ground using 14 AWG (1.6 mm) wire with a ring lug. Use the 5/16 in. panhead screw shipped with the backplane to secure the ring lug to the backplane PE ground terminal. 

• As with any hazardous voltage wiring, make sure that all wiring and connections meet applicable electrical codes and commonsense practices. Mount terminal bases and backplanes in an area, position, or cabinet that prevents accidental or unauthorized access to wiring that carries hazardous voltages. 

• Do not use the cFP-DI-304 as the only isolating barrier between human contact and working voltages higher than 250 Vrms. 

• Operate the cFP-DI-304 only at or below Pollution Degree 2. Pollution Degree 2 means that only nonconductive pollution occurs in most cases. Occasionally, however, temporary conductivity caused by condensation must be expected. 

• Operate the cFP-DI-304 at or below Measurement Category II. Measurement Category II is for measurements performed on circuits directly connected to the low-voltage installation. This category refers to local-level distribution, such as that provided by a standard wall outlet.