Design Features

The NTX-240 Substation Controller, another mid-size version of the ACS NTX series substation systems, provides complete substation management functionality. It also adds the ability to interface to a large amount of data from IEDs and to upgrade legacy RTUs interfacing to a medium to large amount of locally-wired I/O devices in the substation. It does not provide any local I/O slots, and is primarily designed to upgrade existing legacy ACS and 2nd source RTUs. Architecturally, the NTX-240 can be described in terms of a client/server relationship. A source produces data (a server) and a destination requires the data (a client). Throughout the NTX-240, clients (such as NTX Gateways to IEDs) produce data, and servers (such as the NTX gateway supplying the virtual databases to the master) receive data. It can also transmit numerous selected subsets of this data to one or more master stations in the master’s native protocol. A medium amount of local I/O can be configured in the NTX-240.


In order to take maximum advantage of the client/server model, the NTX-240 uses a distributed processing architecture. Multiple high-performance ARM9E 32–bit RISC microprocessors, each programmed to support specific functions, are linked together using a peer–to–peer type network. The ARM9E microprocessor-controlled, high capacity NTX quad-serial/Ethernet gateways make it an ideal, low–cost substation solution for data concentrator and protocol converter for small– to medium–sized transmission or distribution substation installation.   


Design Features:

  • Distributed processing architecture, featuring multiple high-performance, ARM9E 32–bit microprocessors with DSP extension in a client/server, peer–to–peer type LAN
  • Embedded Linux operating system (not user-accessible, for secure operating conditions)
  • Legacy protocols from previous Connex/NTU models will be supported, based on demand.
  • Extended temperature range of –10° to 70°C (14° to 158°F)
  • Multiple Virtual RTUTM database mapping
  • Field–programmable; remotely configurable via Ethernet WAN/LAN
  • Sequence–of–events reporting with 1ms resolution
  • Built-in IRIG-B (unmodulated) Time Code Reader and GPS time reference (NMEA 0183) interface (optional external satellite clock/antenna required) or NTP time synchronization, supported via the Ethernet network
  • Optional IEC 611131 and 61499–compliant NTX Logic PLC that executes user–defined control and/or calculation algorithms
  • 2 USB channels: 1 for mini–USB to USB connections to the maintenance channel; 1 to support a thumb drive to update Flash firmware
  • Multiple 10/100 BaseT Ethernet with DNP or Modbus RTU protocol over TCP/IP or UDP client, server or multiples of both, with a high quantity of IP connections available per port
  • Euro card format (3U x 42HP; 9.5” W x 6” H x 12” D); mid-plane motherboard where the front modules contains the majority of the logic (system CPU nodes), and the rear modules contains the corresponding terminations
  • Multiple master/IED isolated communication serial interfaces (configurable per port for RS–232, with or without flow-control, to external modems or fiber optics, or RS–485 for copper)
  • Provides I/O interfaces for legacy ACS and 2nd source RTUS upgrades


Application and Expansion:

The NTX-240 can be used in a traditional centralized equipment rack– or floor-mounted cabinet. The base NTX-240 I/O interfaces support upgrading: 


  • Up to sixteen 16-point DIN rail-mounted DC analog input modules (256 points) or 256 card file-mounted DC analog input modules (256 inputs)
  • Up to eight 32-point DIN rail-mounted digital input modules (256 points) or 16 card file-mounted digital input modules (512 points)
  • Up to 256 control relay outputs
  • Bell 202 FSK modems supported


An NTX System Controller with termination provides a combination of router and dual-serial ports with an Ethernet port as the base communications. An NTX I/O network controller for upgrading DIN rail-mounted analog and digital inputs utilizes a system node slot for up to 256 analog inputs, 256 digital inputs and 2 analog output channels (e.g., to upgrade the ACS Connex 30 or Connex 60 models).  An expanded I/O network controller for upgrading card file-mounted analog and digital inputs will utilize the same system node slot for up the 256 analog inputs, 512 digital inputs, and up to 16 analog outputs (e.g., to upgrade the ACS MPR-3010, MPR-7010, NTU-7510, very large ACS Connex 30 models and many legacy RTUs from other manufacturers).  


With the addition of a binary output controller that will utilize another of the five system motherboard slots, up to 256 external control relays can be upgraded with both momentary (varying contact voltage/current ratings supported) and latching relays. The unit power supply and up to 4 additional NTX quad-serial with Ethernet port gateways (two with the local I/O and binary output controller installed) can be incorporated in the card file mid-plane system motherboard—for a maximum of 18 isolated EIA561 RS-232/RS-485 RJ45 serial ports and 5 high-capacity 10/100 BaseT Ethernet ports. 


The NTX Explorer software makes it easy to configure or expand the type and number of ports and protocols communicating with the master stations or IEDs, defining local I/O points, and/or other components. 


Key Specifications (see product brochure for complete list)
Card file dimensions
Complies with IEEE 1101/11 & IEEE 1011.10 standards; 42 HP wide x 3U high (9.5” W x 6” H x 12” D) for single Euro-card format modules, bottom wall with front and rear access, or rear-mounted with front-only access
Option: can be supplied in a standard 19” W x 5.25” H x 12” D card file for rack mounting
The half- or full-size card file contains the power supply, a 5-slot node system mid-plane node motherboard
Database capacity
14,000 data values per system controller and NTX gateway
Serial port connections
EIA 561 standard RJ45 DTE connectors
Ethernet connection
RJ45, with multiple client, server and multiples of both; IP configurable
Serial communication ports
Isolated digital EIA561 RS–232 DTE (with or without handshaking) or RS–485 serial interfaces, configurable per RJ45 port
Optional external fiber optic transceiver
Serial analog operation channel
Two– or four–wire (9600 baud with optional external modem; 1200 baud with optional internal Bell 202 modem)
Serial baud rate
300 to 115,200 bits per second, selectable per port
Local programmable logic
NTX Logic (optional) is a Programmable Logic Controller (PLC) application that runs on the NTX System Controller platform. It supports all of the standard IEC 61131 and 61499 control program languages, as well as Flow Chart
Binary input capacity
256 points, in groups of 32 inputs maximum, DIN rail-mounted; or 512 card file-mounted maximum
Configurable per point as binary with time (SOE 2), binary without time (Status), or Form A or two consecutive as Form C counters
Counter input capacity
128 Form C or 256 Form A points, in groups of one input (Binary inputs configurable for either Form A or Form C counters)
DC analog input capacity
256 points, in groups of 16 inputs, DIN rail- or card file-mounted
Analog inputs
Standard: 0 ± 1 mA (optional: ± 10 mA, ± 1.5 mA, 4-20 mA, ± 5 VDC, etc.)
DC analog output capacity
2 analog outputs, in groups of 1 channel (isolated 4–20 mA)
Control output capacity
Optically isolated 16 x 16 matrix drivers for up to 256 relays (in groups of 6, 8 or 16 relays)
Power supply voltages
24, 48, 130, 260 VDC; 115, 220 VAC
Power consumption
30 watts, typical
Optional battery charger
Sealed lead–acid; 6 hours backup, typical


Misc. Options

Custom enclosures, with or without optional heater

Other external terminal block options

Bell 202 or 9600 baud 4–wire multi–drop telephone modem

External GPS satellite clock and antenna

More Information

For more information call 800.831.7223 or contact This email address is being protected from spambots. You need JavaScript enabled to view it.



NTX-240 substation controller Brochure PDF


ACS NTX-240 substation controller Product Brochure

NTX-240 block diagram Brochure PDF


ACS NTX-240 block diagram Brochure