Industrial Automation relies on reading field variables that are still predominantly analog values like 4-20 mA, 1 to 5 VDC, and 0 to 10 VDC. These analog signals can be representative of temperature, pressure, gas, flow, etc. Isolation plays a big part in eliminating ground loops and improving signal quality.
VP Process Inc. has released the SDAFE™, a Software Defined Analog Front End module. This small module (1.9" x 0.95") can be set via it's SPI interface to be either 4-20 mA, 1 to 5 VDC, or 0 to 10 VDC input (other ranges available) and is available as an Isolated (2.5KV Isolation) module:
VPE-3001B SDAFE™
or as a Non-Isolated Module:
VPE-3051B SDAFE™
The PI-SPI-DIN Automation Series of products have SDAFE's available as their primary analog inputs, and an expansion module is available to allow for up to 80 SDAFE™ analog channels to be used as one system.
The SDAFE™ Block Diagram
Specifications:
Power:
3.3VDC or 5.0VDC (Raspberry Pi and Arduino Compatible)
SPI:
MISO Data Input, Active High
MOSI Data Output, Active High During Chip Select, Open Collector Output
SCK Clock
/CS Chip Select, Active Low
Speed Up to 100KHz
Input:
Type 1: (Default) 0 - 20 mA 0 - 20000 Units: mA
Type 2: 0 - 20 mA 0 - 10000 %
Type 3: 4 - 20 mA 0 - 10000 %
Type 4: (Default) 0 - 5 VDC 0 - 5000 Units: VDC
Type 5: 0 - 5 VDC 0 - 10000 %
Type 6: 1 - 5 VDC 0 - 10000 %
Type 7: (Default) 0 - 10 VDC 0 - 10000 Units: VDC
Type 8: 0 - 10 VDC 0 - 10000 %
Type 9: 2 - 10 VDC 0 - 10000 %
AD Converter:
Resolution: 15 bits
Conversion:
15 SPS (Samples per Second)
Accuracy:
+/- .005 reading for mA and VDC Types 1, 4 and 7
+/- .01 reading for mA and VDC Types 2, 3, 5, 6, 8 and 9
Over Range:
Inputs have up to 25% Over Range per input type
Error Status:
Status Register: Over Range Detection when input greater than 125%
Reverse Polarity Detection
Indicators:
Blue LED: Power ON
Green LED: ON When Chip Select Active (Low)
Connections:
J2 Non-Isolated Side
Pin 1: +V (+3.3VDC or +5VDC)
Pin 2: 0V (Common)
Pin 3: MOSI
Pin 4: CLK
Pin 5: /SS (Chip Select)
Pin 6: MISO
Pin 7: no connection (Reserved for HART Module)
Pin 8: no connection (Reserved for HART Module)
Pin 9: no connection (Reserved for HART Module)
Pin 10: no connection (Reserved for HART Module)
J1 Isolated Side (Non-Isolated Side for VPE-3051A)
Pin 1: no connection
Pin 2: no connection
Pin 3: Common
Pin 4: Common
Pin 5: Signal Input mA or VDC
Pin 6: Signal Input mA or VDC
Pin 7: Common
Pin 8: Common
Dimensions:
1.95" x 0.95"
Headers on standard 0.1" spacing