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RS-232/485 (Modbus/RTU) network adapters

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Easy Maintenance 

The NA-4020/4021 series network adapter can be expanded by adding up to 32 I/O modules. It can provide spring type, removable terminal blocks (RTBs) that allow you to preserve field wiring before replacing an I/O expansion module. Each I/O expansion module can be replaced quickly and easily. 

Dimensions (unit = mm)

Common Specifications
Field Power
Rated Voltage 11 to 28.8 VDC, 24 VDC typical
Current in Field Power Contact Max. 10 A
System Power to I/O Driver Optical isolation
Physical Characteristics
Dimensions 45 x 99 x 70 mm (1.77 x 3.90 x 2.76 in)
Weight 150 g
Mounting DIN rail
Environmental Limits
Operating Temperature -10 to 60°C (14 to 140°F)
Storage Temperature -40 to 85°C (-40 to 185°F)
Ambient Relative Humidity 5 to 95% (non-condensing)
Altitude Up to 2000 m
Note Please contact Moxa if you require products guaranteed to function properly at higher altitudes.
Standards and Certifications
Safety UL 508
EMI 61000-3-2; EN 61000-3-3; EN 61000-6-4; FCC Part 15, Subpart B, Class A
EMS EN 61000-4-2, EN 61000-4-3, EN 61000-4-4, EN 61000-4-5,
EN 61000-4-6, EN 61000-4-8, EN 61000-4-11, EN 61000-6-2
Vibration IEC-68-2-6 (2 g's during operation)
Warranty Period 2 years
Details See www.moxa.com/warranty
NA-4020/4021 Specifications
Serial Communication Parameters
Parity None, Even, Odd
Data Bits 7, 8
Stop Bits 1, 2
Baudrate 1200 to 115200 bps
Signals • NA-4020: Data+, Data-, Gnd, DIR (5-contact terminal block)
• NA-4021: TxD, RxD, Gnd (9-pin D-Sub female)
Software Features
Protocols Modbus/RTU, Modbus/ASCII
Modbus Address 00 to 99 (set by rotary switches)
Programming Library MXIO DLL library for Windows; Supports Visual Basic, Visual C++, Borland C++ Builder, .net, VB/VC.NET
Number of I/O Modules Supported Max. of 32
Power Requirements
Power Input 11 to 28.8 VDC, 24 VDC typical
Power Consumption 70 mA @ 24 VDC
Current for I/O Modules Max. 1.5 A @ 5 VDC
MTBF (mean time between failure)
Time NA-4020: 4,695,360 hrs
NA-4021: 4,721,640 hrs
Database Telcordia (Bellcore)

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Available Models

  Model No. Description
NA-4020 RS-485 network adaptor (Modbus/RTU)
NA-4021 RS-232 network adaptor (Modbus/RTU)

Compatible Modules

  Model No. Description
M-1600 16 digital inputs, sink, 24 VDC
  Model No. Description
M-7001 System power module
  Model No. Description
M-4410 4 analog outputs, 0 to 10 V, 12 bits
  Model No. Description
M-4402 4 analog outputs, 4 to 20 mA, 12 bits
  Model No. Description
M-1800 8 digital inputs, sink, 24 VDC
  Model No. Description
M-1601 16 digital inputs, source, 24 VDC
  Model No. Description
M-1801 8 digital inputs, source, 24 VDC
  Model No. Description
M-1451 4 digital inputs, 220 VAC
  Model No. Description
M-1450 4 digital inputs, 110 VAC
  Model No. Description
M-2801 8 digital outputs, source, 24 VDC, 0.5A
  Model No. Description
M-3810 8 analog inputs, 0 to 10 V, 12 bits
  Model No. Description
M-3802 8 analog inputs, 4 to 20 mA, 12 bits
  Model No. Description
M-6200 2 analog inputs, RTD: PT100, JPT100
  Model No. Description
M-6201 2 analog inputs, thermocouple
  Model No. Description
M-7805 Potential distributor module, 8-ch, 24 VDC
  Model No. Description
M-7002 Field power module
  Model No. Description
M-2600 16 digital outputs, sink, 24 VDC, 0.3A
  Model No. Description
M-2601 16 digital outputs, source, 24 VDC, 0.3A
  Model No. Description
M-2800 8 digital outputs, sink, 24 VDC, 0.5A
  Model No. Description
M-7804 Potential distributor module, 8-ch, 0 VDC
  Model No. Description
M-2450 4 relay outputs, 24-VDC/230-VAC, 2 A

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