DFM-400P Pulse Input Field Module for Building Automation
The DFM-400P Pulse Input Field Module provides specialized I/O to Delta’s BACnet™ controllers in the form of four pulsed inputs. It communicates directly on a RS-485 BACnet MS/TP network, where it functions as an independent BACnet device. The pulse input points are accessible to other BACnet devices over the BACnet MS/TP network.


The DFM-400P is ideal for monitoring electrical, water, gas, and various flow meters or use in a diverse range of other applications that require pulse input monitoring. It is capable of handling pulses from 0 to 200 Hz on all four pulse inputs and 0 to 2000 Hz on two pulse inputs.

Additional strategies associated with the pulse counter values can be programmed through GCL+ in other controllers on the network.


  • Native BACnet device
  • Pulse totals are backed-up in EEPROM during power outage
  • Key pulse count values are mapped to standard BACnet variables for multi-vendor integration
  • BACnet MS/TP network communication
  • Easy-to-mount housing
  • Derived Network Addressing (DNA) for simple integration into a standard network architecture
  • Incorporates Delta’s MS/TP autobaud feature which removes the need to manually set up the device’s baud rate


2 Pulse inputs (PI1 and PI2) @ 0 - 2000 Hz each

2 Pulse inputs (PI3 and PI4) @ 0 - 200 Hz each

Monitors either dry contact or open collector signals

Jumper selectable DEBOUNCE circuitry for mechanical contacts (for pulses less than 200 Hz)


8-bit Processor with internal A/D, Flash and RAM

Software clock

LED status indication of the CPU

Device Address

Set via DIP switch or software setup

DIP switch address range: 1 to 99 per BACnet MS/TP network segment

Software switch address range: as per the BACnet standard

Supports Delta’s derived network addressing (DNA) scheme

Communications Ports

NET1 – RS-485 LAN, BACnet MS/TP @ 9600, 19200, 38400 or 76800 bps (default) (maximum of 99 devices per BACnet MS/TP segment)


Removable screw-type terminal connectors

Wiring Class

Class 2


24 VAC

4 VA


32° to 131°F (0° to 55°C)

10 - 90% RH (non-condensing)


6.5 x 4 x 1.8 in. (16.8 x 10 x 4.7 cm) with housing

0.4 lb. (184 g) with housing





UL 916 Listed

C-UL Listed

BTL Listed

  • IO Expansion Modules (DFMs)