Schneider 170NEF11021C Modbus Plus Adapter

The Schneider 170NEF11021C connects Momentum I/O devices to Modbus Plus networks. This communication adapter sits between the field bus and I/O modules. You will find it in distributed control systems across factories and process plants. It converts Modbus Plus messages into local I/O data. Therefore, this unit enables seamless peer-to-peer communication between controllers.

This adapter measures 95 mm in height and 38 mm in width. Its depth reaches 70 mm for DIN rail mounting. The unit weighs approximately 0.25 kilograms. It contains one 16-bit processor and two optical isolation transformers. One 9-pin D-sub connector provides the Modbus Plus interface. Additionally, you get six status LEDs for network diagnostics.

Key Technical Specifications

Parameter	Value
Manufacturer	Schneider Electric
Model	170NEF11021C
Product Type	Modbus Plus Communication Adapter
Network Protocol	Modbus Plus (1 Mbps)
Network Connector	9-pin D-sub female
Node Addressing	1 to 64 (rotary switches)
Isolation	1500 VAC (optical)
Local Bus Interface	Momentum I/O backplane
Processor	16-bit @ 40 MHz
Memory	128 KB RAM, 256 KB Flash
Height	95 mm
Width	38 mm
Depth	70 mm
Weight	0.25 kg
Status LEDs	6 (PWR, COM, ACT, ERR)
Energy Storage	≈ 120 µF (capacitive)
Power Consumption	150 mA @ 5 VDC
Operating Temperature	0°C to +60°C
Mounting Method	DIN rail or panel

Internal Architecture and Energy Storage

The Schneider 170NEF11021C stores minimal energy in its filter capacitors. Small electrolytic capacitors hold approximately 120 microfarads total capacitance. A 16-bit processor runs the Modbus Plus protocol stack at 40 MHz. This processor manages token passing and data exchange between nodes. Two optical isolation transformers protect the local I/O from network transients. The adapter includes 128 KB of RAM for message buffering. You get 256 KB of flash memory for firmware storage. Rotary switches on the front set the node address from 1 to 64.

Connection Interfaces and Wiring Details

You will find a 9-pin D-sub female connector on the front panel. This connector carries the Modbus Plus shielded twisted-pair cable. Connect the A wire to pin 4 and the B wire to pin 5. Connect the shield drain wire to pin 1 (ground). The Schneider 170NEF11021C also includes a 20-pin backplane connector. This connector attaches directly to Momentum I/O modules. Six LEDs show power, communication activity, and fault status. A green PWR LED lights up when the adapter receives 5 VDC. A yellow COM LED flashes during active network transmission.

Installation and Configuration Steps

You mount this adapter onto standard 35 mm DIN rail. First, hook the top clip onto the rail edge securely. Then, press the bottom downward until it locks in place. Set the rotary switches to a unique Modbus Plus address. Turn the upper switch for tens digit and lower switch for ones digit. The Schneider 170NEF11021C connects to a Momentum I/O base on the right. Slide the adapter into the base until the latch clicks. Connect the Modbus Plus cable to the 9-pin D-sub connector. Apply power to the system and verify all LEDs. Use Concept or ProWORX software to configure network parameters. Test communication with other nodes before final deployment.