Each MST version has a fixed baud rate and protocol.

The Modbus versions of the MST mimic the registers of Modicon’s Ethernet Communication Adapter with additional registers and capabilities. For example, the MST makes it possible to read the state of the outputs (4x registers 101 through 132). The MST also contains a configurable watchdog timer to zero the output registers whenever communication is lost.

MST applications

• Add Momentum I/O to a Modbus serial network.
• Connect to a modem for dial-up I/O
• Put Momentum I/O on a Modbus or RNIM radio network
• Put Momentum I/O on a POWERLOGIC® or POWERLINK® network.
• Put Momentum I/O on a Modbus power management system
• Provide a serial interface for motor drives
• Build a Serial to Seriplex™ bridge.

  MST Benefits

• No programming required
• Ability to read outputs
• Watchdog operates on all 32 output registers
• Add multiple I/O to Ethernet when out of IP addresses (requires a bridge)
• Configurable default output condition

  Momentum Compatibility

  The MST supports any Momentum I/O base, auto-detects the base ID code and reports this in 4x register 204. The MST does not support any Option Adapters.

  Power

  The Momentum base powers the MST through the base/tophat connector. The MST power consumption is 0.25 watts, far less than the 5-watt minimum power that Modicon specifies Momentum bases provide. Devices powered by the +5 Volts on the RS-232 connector must not draw in excess of 100mA since this may exceed the power output of the Momentum base.

  Configuration

  The address and parity of the module is configured via a six-position DIP-switch on top of the module. Valid addresses are 1 through 31. Power-up and default output conditions are user configurable by setting the outputs and writing the default-save register. This feature permits automatic base configuration on power-up.

  The communication-loss watchdog timer is configured via Modbus write. The default timer value is 30 seconds. The default output condition is all outputs off. Future MST versions may have other configuration options.

  LEDs

  The MST has three LEDs. The green LED indicates the module is powered and configured (on steady) or powered but not configured (flashing slowly). The amber LEDs indicate when the module is transmitting (TX on) and receiving (RX on).

  Statistics

  There are statistics registers to indicate tophat/base communication health, last I/O module error, and I/O module communication error count.

  Pinouts

  The following tables illustrate the connector pinouts for each MST variant.

  RJ45 RS-232 Port
  Pin	Function
  1	+5VDC (100 mA max. output)
  2	No Connection
  3	TX (out)
  4	RX (in)
  5	Signal GND
  6	RTS (out)
  7	CTS (in)
  8	Chassis GND

  
  

  RJ45 RS-485 Port
  Pin	Function
  1	RX - (in -)
  2	RX + (in +)
  3	TX + (out +)
  4	No Connection
  5	No Connection
  6	TX -(out -)
  7	No Connection
  8	GND

  
  

  5-pin Screw Terminal RS-485 Port
  Pin	MSTD-0 (Old Function)	MSTD-1,2,3 (New Function)
  1	GND	TX +
  2	TX - (out -)	TX -
  3	TX + (out +)	RX +
  4	RX - (in -)	RX -
  5	RX + (in +)	GND

  
  

  5-pin Screw Terminal RS-232 Port
  Pin	Function
  1	TX
  2	RX
  3	Signal GND
  4	RTS
  5	CTS

  
  

  3-pin Screw Terminal RS-485 Port
  Pin	Function
  1	+
  2	-
  3	GND

  
  

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  Ordering Instructions

  The MST is available in the following configurations:

  In the part number:
  
  

  Contact the factory for additional protocols and baud rates.

  SPECIFICATIONS:

  Dimensions: 4.9” wide x 2.5” tall x 1.2” deep (124 x 64 x 30 mm). Approximately 2 ounces (56g) net. Durable polycarbonate enclosure.

  Power Requirements: From TSX Momentum I/O base. 5VDC, 50mA max.

  Serial Port: Optically isolated; single RS-232 or RS-485. Select protocol, baud rate and connector type by part number (see Ordering Information).

  Indicators: Green LED Power indicator; amber LED indicators for Transmit and Receive. Three total indicators.

  Configuration Registers: Stored in EEPROM; returned to factory defaults by setting device address to zero and cycling module power.

  Statistics: Module health, last communication error, error count.

  Operating Conditions: 0 to 50 degrees C operating temperature; -40 to 80 degrees C storage. Humidity up to 90% noncondensing. Pressure altitude -200 to +10,000 feet MSL.

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