Specifications

D1000 modules may be powered with an unregulated +10 to +30Vdc.
Power-supply ripple must be limited to 5V peak-to-peak, and the instanta-
neous ripple voltage must be maintained between the 10 and 30 volt limits
at all times. The modules contain a low voltage detection circuit that shuts
down all circuits in the module at approximately 9.5 Vdc. All power supply
specifications are referred to the module connector; the effects of line
voltage drops must be considered when the module is powered remotely.
All D1000 modules employ an on-board switching regulator to maintain
good efficiency over the 10 to 30 volt input range; therefore the actual current
draw is inversely proportional to the line voltage. D1000 modules without
sensor excitation consume a maximum of .75 watts and this figure should
be used in determining the power supply current requirement. For example,
assume a 24 volt power supply will be used to power four modules. The total
power requirement is 4 X .75 = 3 watts. The power supply must be able to
provide 3 / 24 = 0.125 amps.
For modules with sensor excitation, consult individual data sheets for power
requirements.
The low voltage detection circuit shuts down the module at approximately
9.5Vdc. If the module is interrogated while in a low power supply condition,
the module will not respond. Random NOT READY error messages could
indicate that the power supply voltage is periodically drooping below the 10V
minimum.
In some cases, a small number of modules may be operated by “stealing”
power from a host computer or terminal.
Small systems may be powered by using wall-mounted calculator-type
modular power supplies. These units are inexpensive and may be obtained
from many retail electronics outlets.
Chapter 7
Power Supply