Design Features

The NTX-220 Substation Controller, the mid-size version of the ACS NTX series substation systems, provides complete substation management functionality. It also adds the ability to interface to a very large amount of data from integrated IEDs, and to a medium to large amount of data from hardwired local I/O devices in the substation. The NTX-220 is designed with multiple 32-bit CPUs operating within a client/server architecture. NTX-220 clients (such as the NTX gateway to IEDs) provide data that is received and processed at the server level in the NTX master gateway supplying the virtual databases to the master. Multiple user-defined subsets of this data can also be transmitted to one or more master stations in the master’s native protocol. A medium amount of local analog and digital inputs can be configured in the six input module motherboard slots available. With the addition of an external expansion card file, these inputs are expandable to the maximum of 256 inputs per local interface node. Control relay outputs are also expandable to 256 relay outputs per control system node, utilizing externally mounted control relay modules with varying voltage and current contact ratings available. 

In order to take maximum advantage of the client/server model, the NTX-220 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 84HP; 19” W x 5.25” 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–232C, with or without flow-control, to external modems or fiber optics, or RS–485 for copper)


Application and expansion:

The NTX-220 can be used in a traditional centralized equipment rack– or floor-mounted cabinet. The base NTX-220 has a six-slot I/O motherboard, which supports any combination of these modules in the slots: 


  • up to six 16-point DC analog input modules
  • up to six 32-point digital input modules
  • up to six Bell 202 FSK modems 


The I/O is expandable beyond the base 6-slot I/O motherboard using  a separate analog (up to 256 points maximum) and/or digital (up to 256 points maximum) input expansion card file(s) with 8 or 16 additional input module slots of the same card file dimensions.  An NTX System Controller with termination provides a combination of router and dual-serial ports, with an Ethernet port as the base communications gateway. An NTX internal I/O network controller is piggybacked on the NTX System Controller for up to 256 analog inputs, 256 digital inputs and 2 analog output channels. 


With the addition of a binary output controller that will utilize one of the 5 system motherboard slots, up to 256 external control relays can be equipped with both momentary (varying contact voltage/current ratings supported) and latching relays. The unit power supply and up to four additional NTX quad-serial with Ethernet port gateways (three with the 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. 


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; 84 HP wide x 3U high (19” W x 5.25” H x 12” D) for single Euro-card format modules, bottom wall- or 19” rack-mounted with front and rear access
The full-size card file contains the power supply, a 5-slot node system mid-plane motherboard and a 6-slot I/O mid-plane motherboard
Time clock
On–board UTC time/date clock, non–volatile; internal time code reader for unmodulated IRIG–B (with P1344 extensions) time synchronization; GPS clock time synchronization (NMEA 0183 protocol) with optional antenna, or NTP via Ethernet
Database capacity
14,000 data values per system controller and NTX gateway
Serial port connections
EIA561 RJ45 connectors
Ethernet connection
RJ45, with multiple client, server and multiples of both; IP configurable
Serial communication ports
Isolated digital RS–232C DTE (with or without handshaking) or RS–485 serial interfaces, configurable per 9–pin 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 with termination module. It supports all of the standard IEC 61131 and 61499 control program languages, as well as Flow Chart
Binary input capacity
192 points, in groups of 32 inputs (for the available six base I/O module slots)
512 inputs maximum with an expansion I/O controller mode and card file
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 utilizing the six base card file and expansion card file I/O slots, in groups of one input
DC analog input capacity
96 points, in groups of 16 inputs (256 inputs maximum with an expansion I/O controller and card file)
Standard: 0 ± 1 mA (optional: 4–20 mA, 0 ± 1.5 mA, 0 ± 2 mA, 0 ± 10 mA, 0 ± 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
20 watts, typical
Optional battery charger
Sealed lead–acid; 6 hours backup, typical
Demo section
200 mm x 108 mm x 70 mm (8” W x 4.25” H x 2.75” D)
35 mm DIN rail


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



NTX-220 substation controller Brochure PDF


ACS NTX-220 substation controller Product Brochure

NTX-220 block diagram Brochure PDF


ACS NTX-220 block diagram Brochure