Acromag, Inc. Tel: 248-295-0880
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Model SP33X-0700
4-Wire DC I/V Signal Splitter w/USB
BLOCK DIAGRAM
How It Works
Key Points of Operation
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Unit is DC powered and power is
Isolated.
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Input is Differential
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Dual Isolated Output Channels
with tandem current and voltage
output terminals.
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Input circuit ground is common
to USB ground.
This transmitter uses a 32-bit microcontroller and a high-resolution 24-bit A/D to
digitize the input signal and communicate to each output DAC via an SPI bus using
digital isolators. This signal is transmitted to 16-bit output DACs which drive
separate voltage and current terminals with a shared return. Each output range is
user-configured. Power for the isolated input and isolated output circuits is
provided via an isolated fly-back converter that operates on voltage wired to the
power terminals at TB5, or wired to optional bus power terminals along the DIN rail.
Set up involves selecting the input range (current or voltage), selecting the output
range at each output (current or voltage), selecting a filter level, and scaling your
input range endpoints to each output range zero/full-scale endpoints. I/O scaling
can also be done in reverse to produce a reverse acting output signal. Refer to the
block diagram above to gain a better understanding of transmitter operation.
The input/USB, each output, and power circuits are isolated from each other. This
unit does not draw power from USB. The USB port ground is common to the input
circuit ground. The USB port ground of most PC’s i
s also common to the USB cable
shield and earth ground. Input sensors could be grounded or ungrounded. For this
reason, it is recommended that USB signals be isolated when connected to a PC to
prevent a ground loop from occurring between the PC earth ground and a grounded
input sensor, which would have the negative effect of pulling the input bias supply
to ground and clipping any negative range.