MEN M36N User manual

®
Embedded Solutions
M36N – 8/16 Analog
Inputs, 16 Bits
20M036N00 E2 – 2009-07-27
User Manual
Configuration example

M36N - 8/16 Analog Inputs, 16 Bits
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M36N - 8/16 Analog Inputs, 16 Bits
The M36N is a 16-bit analog M-Module™ for a wide range of standard input
requirements such as 16 channels single-ended voltage or current and 8 channels
differential voltage or current. The isolated supply voltages are generated by an
onboard DC/DC converter, which supports an extended temperature range of -40 to
+85°C. A fast A/D converter and auto-incrementation of the multiplexer channel
make the M-Module™ ideal for fast sampling. The complete acquisition time of an
M36N is 130µs for all 16 channels and the precision is typically 0.05% over the
whole temperature range. The M36N features totally automatic adjustment of each
channel and each input range.
The FPGA implemented on the M36N controls the signal conditioning and in
addition offers space for application-specific function extensions of the board. What
is more, a soft-core processor can be implemented into the FPGA for intelligent pre-
data-processing or additional functions like noise-shaping. For doing this it is
optionally possible to use up to 6MB non-volatile memory as well as assemble up to
32 MB DDR2 DRAM.
The M36N is designed for a large range of applications, for example in automated
test environments or process control systems.
The M36N is based on the M-Module™ ANSI mezzanine standard. It can be used
as an I/O extension in any type of bus system, i.e. CPCI, VME or on any type of
stand-alone SBC. Appropriate M-Module™ carrier cards in 3U, 6U and other
formats are available from MEN or other manufacturers.

Technical Data
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Technical Data
A/D Conversion
• 16 bits
• Total acquisition time: 130µs for all 16 channels
• Precision: ±0.05% typ. (over the whole temperature range)
• Noise: ±3 LSB of mean value, delta = 0.8 (for gain factor 1)
• Electrically isolated (500V isolation)
• Programmable gain factor of 1, 2, 4, 8 or 16
• Offset max. 4 LSB (25°C)
• Full-scale error max. 4 LSB (25°C)
• Software-selectable unipolar or bipolar operation
• Sample and hold possible with external trigger
• Autoincrement of channel number
Single-Ended Input Signal Conditioning
• Voltage or Current Inputs
- 16 analog inputs, single-ended
- High input voltage tolerance
- Cross-talk less than 56db
- Low-pass filter 1kHz
• Voltage Measurement
- Precision: ±0.05%
- Voltage max. to IGND: ±15V (a higher voltage could destroy the board)
- Voltage full scale bipolar operation: ±10V
- Voltage full scale unipolar operation: 0..10V
- Input resistance: 100 kOhm, ±10%
• Current Measurement
- Precision: ±1%
- Current max.: ±25mA
- Current full scale: ±20mA, UA = ±1.25V
- Load resistance: 62.5 Ohm, ±0.1%
Differential Input Signal Conditioning
• Voltage or Current Inputs
- 8 analog inputs, differential
- High common mode range ±200V
- Cross-talk less than 60db
- Low-pass filter 3kHz
• Voltage Measurement
- Precision: ±0.05%
- Voltage max.: ±200V (common mode)
- Voltage full scale bipolar operation: ±10V
- Voltage full scale unipolar operation: 0..10V
- Input resistance: 400 kOhm typ.
!

Technical Data
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• Current Measurement
- Precision: ±1%
- Current max.: ±25mA
- Voltage max. to IGND: ±200V
- Input resistance: 62.5 Ohm, ±0.1%
FPGA
• FPGA Altera® Cyclone® II EP2C20
- 18,752 logic elements
- 239,616 total RAM bits
• Standard factory FPGA configuration:
- ADC control logic
- 16Z083_MM2WB – M-Module™ to Wishbone interface
- 16Z045_FLASH – Flash controller
Miscellaneous
• External trigger (isolated, rising-edge sensitive)
• External binary input
Peripheral Connections
• Via front panel on a shielded 25-pin D-Sub receptacle connector
• Via carrier board (rear I/O)
M-Module™ Characteristics
• A08, D16, INTA, IDENT
Electrical Specifications
• Isolation voltage:
- 500V DC between isolated side and digital side
- 500V DC between shield and isolated ground. Voltage between the connector
shield and isolated ground is limited to 180V using a varistor as a protective
device; AC coupling between connector shield and isolated ground through
47nF capacitor
• Supply voltages/power consumption:
- +5V (4.85V..5.25V), 500 mA typ. (with single-ended input, 10V at all 16
inputs )
• MTBF: 596,848h @ 40°C according to IEC/TR 62380 (RDF 2000)
Mechanical Specifications
• Dimensions: conforming to M-Module™ Standard
• Weight: 102g
Environmental Specifications
• Temperature range (operation):
--40..+85°C
- Airflow: min. 10m³/h

Technical Data
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• Temperature range (storage): -40..+85°C
• Relative humidity range (operation): max. 95% non-condensing
• Relative humidity range (storage): max. 95% non-condensing
• Altitude: -300m to + 3,000m
• Shock: 15g/11ms
• Bump: 10g/16ms
• Vibration (sinusoidal): 2g/10..150Hz
• Conformal coating on request
Safety
• PCB manufactured with a flammability rating of 94V-0 by UL recognized manu-
facturers
EMC
• Tested according to EN55011, EN50121-3-2 (limit value category A), EN61000-
4-2 (ESD) and EN61000-4-4 (burst)
Software Support
• MEN Driver Interface System (MDIS™ for Windows®, Linux, VxWorks®,
QNX®, OS-9®)
• For more information on supported operating system versions and drivers see
online data sheet.

Block Diagram
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Block Diagram
M-Module
Interface
M-Module ID
EEPROM
D08,
D16,
A08,
INTA
Isolation
A
D
A
Pregain
Signal
Conditioning
DC
DC
FPGA
SPI
Signal
Start-up
Configuration Reloadable
FPGA Code
Binary Input/
External Trigger
Channel MUX
3.3V TTL
Level Shifting
5V TTL
D08,
D16,
A08,
INTA
CPLD Flash
Memory

Configuration Options
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Configuration Options
Input channels
• Voltage or current
• 8 differential or 16 single-ended
Additional user-defined functions
• Nios® soft core implementation possible
- With up to 32MB SDRAM and up to 6MB non-volatile memory
- For intelligent data pre-processing or additional functions like noise shaping
Please note that some of these options may only be available for large volumes.
Please ask our sales staff for more information.
For available standard configurations see online data sheet.

Product Safety
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Product Safety
Electrostatic Discharge (ESD)
Computer boards and components contain electrostatic sensitive devices.
Electrostatic discharge (ESD) can damage components. To protect the board and
other components against damage from static electricity, you should follow some
precautions whenever you work on your computer.
• Power down and unplug your computer system when working on the inside.
• Hold components by the edges and try not to touch the IC chips, leads, or cir-
cuitry.
• Use a grounded wrist strap before handling computer components.
• Place components on a grounded antistatic pad or on the bag that came with the
component whenever the components are separated from the system.
• Store the board only in its original ESD-protected packaging. Retain the original
packaging in case you need to return the board to MEN for repair.
!

About this Document
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About this Document
This user manual describes the hardware functions of the board, connection of
peripheral devices and integration into a system. It also provides additional
information for special applications and configurations of the board.
The manual does not include detailed information on individual components (data
sheets etc.). A list of literature is given in the appendix.
History
Conventions
This sign marks important notes or warnings concerning proper functionality of the
product described in this document. You should read them in any case.
Folder, file and function names are printed in italics.
Bold type is used for emphasis.
A monospaced font type is used for hexadecimal numbers, listings, C function
descriptions or wherever appropriate. Hexadecimal numbers are preceded by "0x".
Hyperlinks are printed in blue color.
The globe will show you where hyperlinks lead directly to the Internet, so you can
look for the latest information online.
Signal names followed by "#" or preceded by a slash ("/") indicate that this signal is
either active low or that it becomes active at a falling edge.
Signal directions in signal mnemonics tables generally refer to the corresponding
board or component, "in" meaning "to the board or component", "out" meaning
"coming from it".
Vertical lines on the outer margin signal technical changes to the previous issue of
the document.
Issue Comments Date
E1 First issue 2008-04-16
E2 Corrections in Technical Data, in Table 10, Address
map, on page 23, in Chapter 5.3 Registers on page
26 and in Chapter 5.4.3 Reading Data (with Inter-
rupt) on page 29
2009-07-27
!
italics
bold
monospace
hyperlink
IRQ
#
/IRQ
in/out

About this Document
MEN Mikro Elektronik GmbH 10
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Legal Information
MEN Mikro Elektronik reserves the right to make changes without further notice to any products herein. MEN makes no
warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does MEN assume
any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability,
including without limitation consequential or incidental damages.
"Typical" parameters can and do vary in different applications. All operating parameters, including "Typicals" must be
validated for each customer application by customer's technical experts.
MEN does not convey any license under its patent rights nor the rights of others.
Unless agreed otherwise, MEN products are not designed, intended, or authorized for use as components in systems intended
for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which
the failure of the MEN product could create a situation where personal injury or death may occur. Should Buyer purchase or
use MEN products for any such unintended or unauthorized application, Buyer shall indemnify and hold MEN and its officers,
employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable
attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or
unauthorized use, even if such claim alleges that MEN was negligent regarding the design or manufacture of the part.
Unless agreed otherwise, the products of MEN Mikro Elektronik are not suited for use in nuclear reactors or for application in
medical appliances used for therapeutical purposes. Application of MEN products in such plants is only possible after the user
has precisely specified the operation environment and after MEN Mikro Elektronik has consequently adapted and released the
product.
ESM™, ESMini™, MDIS™, MDIS4™, MENMON™, M-Module™, M-Modules™, SA-Adapter™, SA-Adapters™,
UBox™, USM™ and the MBIOS logo are trademarks of MEN Mikro Elektronik GmbH. PC-MIP® is a registered trademark
of MEN Micro, Inc. and SBS Technologies, Inc. MEN Mikro Elektronik®, ESMexpress®, MIPIOS® and the MEN logo are
registered trademarks of MEN Mikro Elektronik GmbH.
Altera®, Arria®, Avalon®, Cyclone®, Nios® and Quartus® are registered trademarks of Altera Corp. Microsoft® and
Windows® are registered trademarks of Microsoft Corp. Windows® Vista™ is a trademark of Microsoft Corp. PXI™ is a
trademark of National Instruments Corp. QNX® is a registered trademark of QNX Ltd. Tornado® and VxWorks® are
registered trademarks of Wind River Systems, Inc.
All other products or services mentioned in this publication are identified by the trademarks, service marks, or product names
as designated by the companies who market those products. The trademarks and registered trademarks are held by the
companies producing them. Inquiries concerning such trademarks should be made directly to those companies. All other brand
or product names are trademarks or registered trademarks of their respective holders.
Information in this document has been carefully checked and is believed to be accurate as of the date of publication; however,
no responsibility is assumed for inaccuracies. MEN Mikro Elektronik accepts no liability for consequential or incidental
damages arising from the use of its products and reserves the right to make changes on the products herein without notice to
improve reliability, function or design. MEN Mikro Elektronik does not assume any liability arising out of the application or
use of the products described in this document.
Copyright © 2009 MEN Mikro Elektronik GmbH. All rights reserved.
Please recycle
Germany
MEN Mikro Elektronik GmbH
Neuwieder Straße 5-7
90411 Nuremberg
Phone [phone]
Fax [phone]
E-mail [email protected]
www.men.de
France
MEN Mikro Elektronik SA
18, rue René Cassin
ZA de la Châtelaine
74240 Gaillard
Phone [phone]
Fax [phone]
E-mail [e-mail]
www.men-france.fr
USA
MEN Micro, Inc.
24 North Main Street
Ambler, PA 19002
Phone [phone]
Fax [phone]
E-mail [email protected]
www.menmicro.com

Contents
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Contents
1 Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1.1 Integrating the Board into a System . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1.2 Installing Driver Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2 Connecting the M-Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.1 Peripheral Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.1.1 Connection via 25-pin D-Sub Connector . . . . . . . . . . . . . . . 15
2.1.2 Connection via Carrier Board/24-pin Connector . . . . . . . . . 15
2.2 Host Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3 Input Conditioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.1 Notes on Pin Assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.2 Single-Ended Acquisition (Current/Voltage). . . . . . . . . . . . . . . . . . . . 18
3.3 Differential Acquisition (Current/Voltage) . . . . . . . . . . . . . . . . . . . . . 20
3.4 Special Acquisition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4 Address Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
5 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5.1 Power Supply. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5.2 Principle of Data Acquisition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5.3 Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
5.4 Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
5.4.1 Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
5.4.2 Reading Data (without Interrupt) . . . . . . . . . . . . . . . . . . . . . 29
5.4.3 Reading Data (with Interrupt) . . . . . . . . . . . . . . . . . . . . . . . . 29
5.5 M-Module Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6.1 Fuse Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
7 Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
7.1 Literature and Web Resources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
7.2 Finding out the Board’s Article Number, Revision and Serial Number32

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Figures
Figure 1. Block diagram of single-ended input . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Figure 2. Block diagram of the differential input . . . . . . . . . . . . . . . . . . . . . . . . 20
Figure 3. Reading data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Figure 4. Position of fuse on M36N. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Figure 5. Labels giving the board’s article number, revision and serial number. 32

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Tables
Table 1. Supported pins of 60-pin plug connector on carrier board. . . . . . . . . . 16
Table 2. 16 single-ended inputs: pin assignment of 25-Pin D-Sub receptacle
connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Table 3. 16 single-ended inputs: pin assignment of 24-pin receptacle connector19
Table 4. 16 single-ended inputs: signal correspondence between 24-pin M-Module
connector and 96-pin carrier board connector . . . . . . . . . . . . . . . . . . . 19
Table 5. 16 single-ended inputs: signal mnemonics of peripheral connectors. . 19
Table 6. 8 differential inputs: pin assignment of the 25-pin D-Sub receptacle
connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Table 7. 8 differential inputs: pin assignment of the 24-pin receptacle connector.
21
Table 8. 8 differential inputs: signal correspondence between 24-pin M-Module
connector and 96-pin carrier board connector . . . . . . . . . . . . . . . . . . . 21
Table 9. 8 Differential inputs: signal mnemonics of peripheral connectors. . . . 22
Table 10. Address map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Table 11. Data format (bipolar operation) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Table 12. Data format (unipolar operation) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Getting Started
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1 Getting Started
This chapter gives an overview of the board and some hints for first installation in a
system.
1.1 Integrating the Board into a System
You can use the following "check list" to install the M-Module on a carrier board for
the first time and to test proper functioning of the board.
;Power-down the system.
;Install the M-Module carrier board in your system without the M-Module.
;Power-up the system.
;Test the carrier board.
;If O.K., power-down the system and remove the carrier board.
;Install the M-Module in slot 0 of the carrier board.
;Insert the carrier board into the system again.
;Power-up the system.
;Load a suitable debugger.
;Read one word from the base address plus 0xFE.
;If a bus error is occurring now, the M-Module is not plugged properly or the
carrier board is not set up correctly (e. g. D201 PLD must be loaded). Please
refer to the carrier board’s user manual for details.
1.2 Installing Driver Software
For a detailed description on how to install driver software please refer to the
respective documentation.
You can find any driver software available for download on MEN’s website.

Connecting the M-Module
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2 Connecting the M-Module
2.1 Peripheral Interfaces
There are two possibilities for connecting peripherals:
• Connection via 25-pin D-Sub connector.
• Connection via the carrier board.
Pin assignment of the connectors depends on the type of input signal conditioning.
The different versions available of the M36N (8 channels differential, 16 channels
single-ended etc.) result in different standard pin assignments. A detailed
description—including the applicable assignment tables—can be found in Chapter 3
Input Conditioning on page 17.
2.1.1 Connection via 25-pin D-Sub Connector
Connector types:
• 25-pin D-Sub receptacle according to DIN41652/MIL-C-24308, with thread bolt
UNC 4-40
• Mating connector:
25-pin D-Sub plug according to DIN41652/MIL-C-24308, available for ribbon
cable (insulation piercing connection), hand-soldering connection or crimp con-
nection
Note: For the M36N to pass the radio disturbance test according to EN55022
shielded cables have to be used.
2.1.2 Connection via Carrier Board/24-pin Connector
When a carrier board with a 96-pin DIN 41612 PCB connection is used for
peripheral signals (for example a 6U VMEbus board), these are fed to the M-
Module through the 24-pin receptacle connector. You can connect up to four 21-pin
connectors to the 96-pin connector (cf. carrier board manual). When these
connectors are used, for each M-Module three pins of the DIN 41612 PCB
connector cannot be used. The pin numbers for the 96-pin connector shown below
are valid for M-Module slot number 3. If other M-Module slots (2, 1 or 0) are used,
the value 8, 16 or 24 must be added as appropriate.
Connector types:
• Two 12-pin receptacles, high-precision, 2.54mm pitch, for square pins
∅0.635mm gold, 6.9mm height
• Mating connector:
Two 12-pin plugs, 2.54mm pitch, square pins ∅0.635mm gold
!

Connecting the M-Module
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2.2 Host Interface
The M-Module supports the following signals of a 60-pin carrier board interface
plug connector:
Note: Only two rows—A and B—of the 60-pin connector are mounted on the
M36N!
Table 1. Supported pins of 60-pin plug connector on carrier board
Connector types:
• Three 20-pin receptacles, high-precision, 2.54mm pitch, for square pins ∅
0.635mm gold, 6.9mm height
• Mating connector:
Three 20-pin plugs, 2.54mm pitch, square pins ∅0.635mm gold
ABC
1/CS GND -
2A01 +5V -
3A02 - -
4A03 - -
5A04 GND -
6A05 - -
7A06 - -
8A07 GND -
9D08 D00 -
10 D09 D01 -
11 D10 D02 -
12 D11 D03 -
13 D12 D04 -
14 D13 D05 -
15 D14 D06 -
16 D15 D07 -
17 /DS1 /DS0 -
18 /DTACK /WRITE -
19 - /IRQ -
20 /RESET - -
1
20
ABC

Input Conditioning
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3 Input Conditioning
Active input filtering is implemented for each channel. Each channel has its own
second-order lowpass filter. Gain is adjusted to an input range of ±10V and the filter
frequency is fixed at about 1kHz for differential input and at about 3kHz for single-
ended input.
3.1 Notes on Pin Assignment
Pin TRIG can be used to trigger the start of external conversion. Channel and gain
will not be changed. TRIG is active on the rising edge.
One bit of additional information can be detected on pin BI. This pin does not
trigger a function on the M-Module. By connecting this pin to IGND in the
connector, you can detect whether the connector on the M-Module is plugged or
not.

Input Conditioning
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3.2 Single-Ended Acquisition (Current/Voltage)
A standard M-Module version for 16 single-ended channels is available (see MEN’s
website). The input voltage range is adjusted to ±10V for full scale and the second-
order lowpass filter limits the input frequencies to 1kHz (can be changed on
request).
The current measurement version has a 62.5-Ωshunt installed for full scale at
±20mA. The gain factor selected by software must be 8!
For each individual channel, space is provided for mounting discrete components,
such as resistors and trimmers, shunt resistors, voltage dividers or filter components.
Figure 1. Block diagram of single-ended input
The following tables give the standard pin assignments for single-ended versions.
Table 2. 16 single-ended inputs: pin assignment of 25-Pin D-Sub receptacle connector
1I014I8
2I115I9
3I216I10
4I317I11
5I418I12
6I519I13
7I620I14
8I721I15
9BI22TRIG
10 IGND 23 -
11 IGND 24 -
12 IGND 25 -
13 IGND
Buffer Filter
Multiplexer
16
114
13 25

Input Conditioning
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Table 3. 16 single-ended inputs: pin assignment of 24-pin receptacle connector
Table 4. 16 single-ended inputs: signal correspondence between 24-pin M-Module
connector and 96-pin carrier board connector
Table 5. 16 single-ended inputs: signal mnemonics of peripheral connectors
23 IGND 24 -
21 IGND 22 IGND
19 - 20 -
17 I7 18 BI
15 I6 16 I15
13 I5 14 I14
11 I4 12 I13
9I310I12
7I28I11
5I16I10
3I04I9
1TRIG2 I8
ABC
1TRIG I8 I0
2I9 I1 I10
3I2 I11 I3
4 I12 I4 I13
5I5 I14 I6
6I15 I7 BI
7- - IGND
8 IGND IGND -
Signal Direction Function
BI in Binary input. Reflects the level of each measure-
ment. Can be used e.g. to detect if a connection
is made, etc.
I0..I15 in Voltage or current input lines 0..15
IGND - Isolated ground
TRIG in Trigger input
23
12
24
1
ABC

Input Conditioning
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20M036N00 E2 – 2009-07-27
3.3 Differential Acquisition (Current/Voltage)
The second standard version supports only 8 channels but has differential inputs.
The input voltage and current rates are the same as for 16 channels (±10V or
20mA). The filter frequency is 3kHz. These rates may also be changed at the
customer's request.
To make proper use of differential acquisition, it is necessary to have basic
knowledge on analog measuring techniques. One common mistake is to believe that
the two wires of a differential input acquisition system can be used like a hand-held
instrument. This is not the case at all. A differential amplifier is an analog
computation circuit. This circuit takes two input voltages referred to ground (!) and
performs analog subtraction.
Unfortunately, in a normal multiplexed acquisition system each input signal has to
pass through a multiplexer. This semiconductor part is only able to handle signals
within the supply voltage range.
The problem is best illustrated by a simple example. Imagine you wish to measure
the voltage and current of a 24V power supply. If you install a resistor divider
between the 24V and ground to obtain a measuring range of 10V, you are not able to
get the voltage across a shunt, because it is outside the working range of the
multiplexer.
Fortunately, the M-Module does not work in this conventional manner. The
M-Module uses one differential amplifier for each channel. Of course, the amplifier
also needs a reference ground for analog calculation but this amplifier has a
common mode range of ±200V. Only the result of the calculation, which is normally
between -10V and +10V, is switched by a multiplexer. This is of great practical
advantage.
As for single-ended acquisition the current measurement version has a 62.5-Ωshunt
installed for full scale at ±20mA. The gain factor selected by software must be 8!
Figure 2. Block diagram of the differential input
The following tables give the standard pin assignments for differential versions.
Filter
Differential
Amplifier
Multiplexer
8
Shunt only for current measurement