This board is a Low Speed variant of the PWM2B to use with low frequency pulse outputs with two frequency range options: 10-100Hz or 0.1-10Hz. and is suitable to interface very low frequency devices with PWM output, such as meteorological sensors, with other equipment requiring analogue input proportional to the duty cycle of the PWM signal.

At very low frequencies the averaging  filter used in the PWM2B presents a trade-off between ripple/response time, that may render it unsuitable for some applications. The PWM2LS uses a different approach by using a micro controller to measure the actual duty cycle of the PWM inputs and generate a high frequency PWM output that improves dramatically the ripple/response time value.

The board requires a 24Vdc power supply and delivers and output level adjustable between 5V and 12V at full scale, making it directly compatible with most commercial drives. If the output voltage is limited to 5-6 V the power supply may be as low as 10V.

Each channel input is optically isolated from the other and the controller. Both output channels share a common ground.

The board is fitted with standard 0.2" terminal boards and can be housed in a commercial plastic enclosure with DIN rail mounting for easy addition to electrical control cabinets.

Specifications

• Number of channels :2
• PWM input:    TTL level, Standard: 10 to 100 Hz, Ultra Low: 0.1 to 10Hz
• Input impedance: app. 1Kohm
• Output: Adjustable 0 to 5..12V
• Linearity: 2% FSD
• Ripple: 50mVpp max. (10-100Hz input)
• Response time:  100ms max. @ 10Hz,  25ms @ 100Hz
• Isolation: Min. 500 Vac
• Power: Nominal 24 Vdc  (Acceptable range 18 to 30Vdc)
• Dimensions: 3.400 x 1.950 x 0.8 in. (87 x 50 x 20 mm)
• Weight: 1.40 oz (0.04 Kg)

Usage

Each input channel is totally independent, therefore they can be connected to different controllers (if required). The outputs share a common ground.

Enclosures

Enclosures for this board can be purchased through distributors or online at:

• Bud Industries - #DMB4771
• Digikey: DMB4771 - #377-1808-ND
• Mouser DMB4771 - #563-DMB-4771
• Newark DMB-4771 - #12T6238
• Velleman: GD3MG
• CamdenBox: CNMB/3/kit