Scanivalve MPS4264, Hardware And Software Manual

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9
MPS4264
Section 2: Introduction
SECTION 2: INTRODUCTION
Overview
The MPS4264 is a 64 channel, intelligent, miniature pres-
sure scanner. Each MPS4264 series scanner incorporates
64 individual piezoresistive pressure sensors. In addition
to the pressure sensors, the MPS4264 integrates all of
the electronics for the analog-to-digital (A/D) conversion
process and a processor running a DSP operating system
supporting the engineering unit conversion process and all
communications overhead. The integral DC/DC converters
allow for a single 9-36Vdc power input. Communications
and data output is via Ethernet, and RS-232 communica-
tions are included for backup and troubleshooting. All 64
pressure sensors share a common reference manifold in
the center of the module. The MPS4264 module has two
pneumatic valves, each servicing 32 pressure sensors. The
valve supports four logic states:
1. Measurement
2. Calibrate
3. Purge
4. Isolate
The valve state is selected by either applying control
pressures (applicable to standard units) or via software
command (applicable to electric actuation units).
The MPS4264 is the first product designed by Scanivalve
to leverage the proprietary “Dynamic CALZ” function.
The function effectively nulls the zero offset of the entire
analog-to-digital conversion process with every single scan.
This feature produces extremely stable sensor outputs and
virtually eliminates all zero drift in the system. With negli-
gible zero drift over time or temperature, the traditional
pneumatic zero correction that was frequently required is
now greatly reduced.
Module Configurations
The MPS4264 is the initial pressure scanner in the
MPS4000 series of pressure scanners. All variants in the
series use the same sensors and valves. However, the elec-
tronics are different for each, and the overall form factor
is slightly different for each model. Because the interface,
form factor and function is different for each variant they
will be covered in separate documents. There are several
options that, for the most part, apply to all three variants.
Pressure Range
Each MPS module can be ordered in the following pressure
ranges:
4 inH
2
O
8 inH
2
O
1psi
5psi
15psi
Valve Actuation
There are two options for actuating the valves in the
MPS4000 series. Each one is optimal for a specific applica-
tion. They are:
Pneumatic “CPx” - This option places a pneumatic
input on each end of the valve. 65psi control pressure
applied to each of the ports individually determines the
position of the valve. This is optimal for any MPS4000
module that will be replacing legacy ZOC33 modules as
the 65psi control pressures are common to both.
Pneumatic “NPx” - This option uses a pneumatic actu-
ator on one end and a spring on the opposing end. The
spring is constantly driving the valve into the measure-
ment, or “Px” mode. This requires no control pressure
to scan and collect data. The opposing pneumatic
control pressure required is 90-120psi.
Pressure Sensors
The 64 pressure sensors in the MPS4000 series are
mounted in groups of four to custom designed ceramic
bases. Sixteen (16) ceramic bases, or “sticks” are RTV’d to a
printed circuit board to create a 32 channel set. This archi-
tecture allows for a single four-channel sensor “stick” to be
replaced at the factory if needed. It also provides double
isolation from any mechanical stresses that may be present
in the assembly.
Each sensor PCB includes four (4) digital temperature chips
and four (4) RTD’s. The RTD’s are for use in analog envi-
ronments (MPS4164) while the digital temperature chips
are used in the intelligent environments (MPS4264). The
digital temperature chips have been mapped to determine
which pressure channels they are most representative of
and are used in the pressure engineering unit conversion
process.
For every MPS4000 series module, two sensor circuit
boards are mounted back to back in the central housing.
The core of the housing is an open volume that is used as a
common reference pressure for all 64 channels. The design
places the sensors deep in the center of the module. Being