GE Fanuc IC670MDL641 Discrete Input Module

The 48 VDC Positive/Negative Input Module (IC670MDL641) provides a single group of 16 discrete inputs, which may be driven by positive or negative logic.

Power Sources

The module receives power from the Bus Interface Unit for its own operation. An external 48

VDC supply is needed to power the input devices.

LEDs

Individual LEDs (logic side), visible through the transparent portion of the module top,

indicate the On/Off status of each input. The PWR LED is On when field and backplane

power are present.

Host Interface

Intelligent processing for this module is performed by the Bus Interface Unit or elsewhere in

the system. This includes configuring features such as input defaults and fault reporting.

The module has 16 bits (two bytes) of discrete input data. A Bus Interface Unit is required

to provide this input data to the host and/or local processor.

Module Operation

A network of resistors, capacitors, and zener diodes establishes input thresholds and provides

input filtering. Optoisolators provide isolation between the field inputs and the module’s logic

components. An oscillator and switch form a sampling circuit that is transparent to the

controller and the LEDs that indicate the state of the inputs. Data from all 16 inputs is placed

into a data buffer. The module’s circuit LEDs show the current states of the 16 inputs in this

data buffer.

Parallel-to-serial converters change input data from the data buffer into the serial format

needed by the Bus Interface Unit.

After checking the Board ID and verifying that the module is receiving appropriate logic power

from the Bus Interface Unit (which is reflected by the state of the module’s Power LED), the Bus

Interface Module then reads the filtered, converted input data.

Positive or Negative Inputs

Inputs for this module can be either positive or negative (all 16 inputs must be the same type).

Both types of signal produce a logic 1 (true) when the switch is closed. Selection of positive or

negative operation is made by the manner in which the external power supply is connected to

the inputs and to the I/O Terminal Block.

Positive inputs receive current from input devices and supply current to the common or

negative power bus. Input devices are connected between the positive power bus and the input

terminals.

Negative inputs provide current to input devices and accept current from the common or

positive power bus. Input devices are connected between the negative power bus and the input

terminal.

 Field Wiring

The following illustration shows terminal assignments for the 48 VDC Positive/Negative

Input Module.

Connection to the A terminals is optional. They can be used as shown on the next page.

The Terminal Block with box terminals has 25 terminals for each module, each of which

accommodates one AWG #14 (avg 2.1mm2 cross section) to AWG #22 (avg 0.36mm2 cross

section) wire, or two wires up to AWG #18 (avg. 0.86mm2 cross section). When an external

jumper is used, the wire capacity is reduced from AWG #14 (2.10mm2) to AWG #16

(1.32mm2).

The I/O Terminal Block with barrier terminals has 18 terminals per module. Each terminal

can accommodate one or two wires up to AWG #14 (avg 2.1mm2 cross section).

The I/O Terminal Block with Connectors has one 20-pin male connector per module. The

mating connector is Amp part number 178289–8. Any tin-plated contact in the AMP D–3000

series can be used with the connector (Amp part number 1–175217–5 for high contact force

receptacle for 20–24 gauge (0.20–0.56mm2) wires), 1–175218–5 for high contact force

receptacle for 16–20 gauge (0.56–1.42mm2)).

Wiring Examples with Auxiliary Terminal Blocks

If the module is installed on an I/O Terminal Block with Box Terminals or an I/O Terminal

Block with Barrier Terminals, an Auxiliary Terminal Block may be required to provide

additional wiring terminals. For the I/O Terminal Block with Wire to Board Connectors,

external connection points are usually be preferred, although an Auxiliary Terminal Block

can be used..

Auxiliary Terminal Blocks have all terminals connected together internally. The Auxiliary

Terminal Block with box terminals has 13 terminals, each of which accommodates one AWG

# 14 (avg 2.1mm2 cross section) to AWG #22 (avg 0.36mm2 cross section) wire, or two wires up

to AWG #18 (avg. 0.86mm2 cross section). The Auxiliary Terminal Block with barrier terminals

has nine terminals, each of which can accommodate one or two wires up to AWG #14 (avg

2.1mm2 cross section).

The following illustration shows how an Auxiliary Terminal Block with Box Terminals can be

used for power connections to an I/O Terminal Block with Box Terminals.

For an I/O Terminal Block with Barrier Terminals, an Auxiliary Terminal Block with Barrier

Terminals might be connected as shown in the following example.