DGH D1450M Modbus Thermistor Input Module Series

The D1450M thermistor input module is part of the DGH’s D1000M Modbus sensor to computer interface data acquisition module family. This input module converts the thermistor temperature sensor input signal from the 2252 Ohm or TD-series thermistor, to digital data, linearises and scales it in °C or °F, and communicates the values using the Modbus RTU protocol to give digital output. The D1450M thermistor input module also contains one digital input and two open-collector digital outputs which may be controlled by the host computer and used to control, for example, solid-state relays. For extra security, it utilises a non-volatile EEPROM (Electrically Erasable Programmable Read Only Memory) to store all user-selectable settings, meaning the values are maintained in the event of power loss. The modules are designed to be compatible with all popular computers utilising RS-232C or RS-485 ports and no software is necessary to start using them, although the utility software is provided. Upon startup, a simple command can be used to setup desired baud rate, parity and other parameters. The D1450M can be mounted on a DIN-rail if required (MK-1 mounting kit required) and can be combined with other D1000M/D2000M modules to provide complete customised data acquisition system for given application.

• Analog-to-digital thermistor input module
• Choice of RS-232 or RS-485 output
• Choice of thermistors: 2252 Ohm at 25°C or TD Series
• Communicates using Modbus RTU protocol
• User-selectable features include °C or °F, baud rate, parity type, channel address and others
• Accuracy: ±0.1°C for 2252Ω and ±0.2°C for TD series
• Resolution: 0.01° (C or F) for 2252Ω and 0.1°(C or F) for TD series
• Common mode rejection: 100dB at 50/60Hz
• Autozero and auto-calibration
• Up to 246 multidrop modules per host serial port (RS-485 only)
• Input protection to 30Vdc
• 1 Digital input with ±30V Voltage levels, switching levels of 3.5V minimum, low, 1.0V maximum and internal pull up resistors for direct switch input
• 2 Digital outputs, open collector to 30V, 30mA maximum load
• Power requirements: Serial = 0.75W
• Temperature range -25°C to +70°C

The applications for the D1450 data acquisition modules include:

• SCADA
• Data monitoring
• Data loggers
• PLC’s
• Process controllers and instrumentation