MMF M208A User manual

Instruction Manual
Manfred Weber
Metra Mess- und Frequenztechnik in Radebeul e.K.
Meissner Str. 58 - D- 1445 Radebeul
Phone [phone] Fax [phone]
Email: [email protected] Internet: www.MMF.de
8 Channel
IEPE
Conditioner
M208A
From Version 1. 12

Manfred Weber
Metra Mess- und Frequenztechnik in Radebeul e.K.
Meissner Str. 58
D-01 5 Radebeul
Phone + 9-351-836 2191
Fax + 9-351-836 29 0
Email [email protected]e
Internet www.MMF.de
Notice: The current version of this document can be downloaded from
http://www.mmf.de/product_literature.htm
Specifications subject to change without prior notice.
© 2009 Manfred Weber Metra Mess- und Frequenztechnik in Radebeul e.K.
No part of this document may be reproduced without the prior written consent of Metra.
Nov/ 22

Contents
1. Application............................................................................................................5
2. The Instrument at a Glance....................................................................................5
2.1. Connectors and Controls................................................................................5
2.2. Display Functions...........................................................................................6
2.3. Menu Structure...............................................................................................6
3. What is IEPE?........................................................................................................7
. What is TEDS?......................................................................................................8
5. Description..........................................................................................................11
6. Power Supply......................................................................................................12
7. Inputs and IEPE Supply.......................................................................................12
8. Outputs................................................................................................................13
9. Grounding and Avoiding Ground Loops ............................................................1
10. Operation ..........................................................................................................1
10.1. Gain Selection............................................................................................1
10.2. Transducer Sensitivity................................................................................1
10.2.1. Introduction........................................................................................1
10.2.2. Normalization of the Display..............................................................16
10.2.3. Normalization of the Amplifier Output...............................................16
10.2. . Sensor Detection.................................................................................17
10.2.5. Entering Transducer Sensitivity in the Menu......................................18
10.2.6. Automatic Sensitivity Adjustment with TEDS Sensors......................18
10.3. Channel Registration..................................................................................19
10. . Measuring Unit...........................................................................................20
10.5. Display Mode.............................................................................................20
10.6. Measuring Display.....................................................................................21
10.7. Relative Magnitude and Overload Indication.............................................21
10.8. Relay Output..............................................................................................22
11. Filters and Integrators........................................................................................2
11.1. Filters ........................................................................................................2
11.2. Integrators..................................................................................................26
11.3. Replacing Filter and Integrator Modules ...................................................28
11. . Detection and Display of Filters and Integrators........................................29
11.5. Switching Off the High Pass Filters...........................................................30
12. Other Settings....................................................................................................31
12.1. Beep...........................................................................................................31
12.2. Serial Interface...........................................................................................31

12.3. Ethernet Interface.......................................................................................31
12. . Switching the IEPE Supply On or Off........................................................31
12.5. Instrument Name........................................................................................32
12.6. Loading Default Settings............................................................................32
12.7. Overload Limits..........................................................................................33
12.8. Firmware Update........................................................................................3
13. PC Connection...................................................................................................35
13.1. Serial Interface...........................................................................................35
13.1.1. Settings...............................................................................................35
13.1.2. Linking Several M208A Units............................................................35
13.1.3. PC Software M208 Control Center.....................................................36
13.1.3.1. Introduction.................................................................................36
13.1.3.2. System Requirements...................................................................36
13.1.3.3. Controls and Functions................................................................37
13.1.3.3.1 Device Menu.........................................................................38
13.1.3.3.2 Device Channels.................................................................... 0
13.1.3.3.3 Channel Overview ................................................................ 3
13.1.3.3. Other menus..........................................................................
13.1.3.3.5 Function Keys....................................................................... 6
13.1.3.3.6 Error Messages...................................................................... 6
13.1. . Communication via ASCII Commands............................................... 7
13.1. .1. Introduction................................................................................. 7
13.1. .2. Control Commands...................................................................... 8
13.1. .3. Read commands...........................................................................50
13.2. Ethernet Interface.......................................................................................52
13.2.1. Introduction........................................................................................52
13.2.2. TCP/IP Settings...................................................................................52
13.2.3. Establishing an Ethernet Connection..................................................53
1 . Reset..................................................................................................................5
15. Calibration.........................................................................................................55
15.1. General.......................................................................................................55
15.1.1. Gain Calibration..................................................................................55
15.2. Display Calibration.....................................................................................55
16. Version and Serial Number................................................................................56
17. Frequently Asked Questions..............................................................................56
18. Technical Data...................................................................................................58
Appendix: Warranty
CE Declaration of Conformity

Thank you for using a vibration instrument from Metra!
1. Application
The 8 Channel IEPE Conditioner M208A was designed for piezoelectric accelerom-
eters, force transducers, pressure transducers and measuring microphones with IEPE
output. The instrument has the following functions:
•Constant current supply of up to eight sensors
•Gain ranges of 0, 20, 0 and 60 dB
•Normalization of transducer sensitivity
•High pass and low pass filtering, optionally single and double integration
In addition, the M208A can display RMS or peak values including physical units.
A relay output is available for controlling external devices. The M208A features a
serial interface for setup and readout by a supplied PC software. The Ethernet inter-
face and the embedded web server of the instrument provide network and Internet
connectivity.
2. The Instrument at a Glance
2.1. Connectors and Controls
5
Figure 1: Front and rear panels
2
4
6
dB
IEPE
OVL
IN O U T
8
SW IT C H E D
O U T P U T
M 2 0 8
8 C H A N N E L IE P E
Display
LEDs for gain indication
Overload LED
Constant current LED
Output socket (channel 8)
Input socket (channel 8)
Shared output (channels 1 to 8)
Arrow keys for menu navigation
Escape key for leaving menus
Key for sensor setup
Key for gain menu
OK key for confirming selections
Key for setup menu
Front Panel:
ear Panel:
+ 1 ...2 6 V D C
3 A
G N D
RESET
P C / M A S TE R
S L AV E
O U T P U T 1 ... 8
R S - 23 2
E T H E R N E T
SE R IAL N O .: M A D E IN G E R M A N Y
Ethernet socket
Serial interface to PC or master unit
Serial interface to slave unit
Outputs of channels 1 to 8 and relay output
Link LED
Active LED
Ground socket
Power supply socket
Reset key
POWER
On/Off switch

2.2. Display Functions
2.3. Menu Structure
6
MENU
1/6: Filter setup
2/6: Display unit
3/6: Display mode
4/6: Channel on/off
5/6: Alarm relay
6/6: Div. settings
1/2: Filter detection
2/2: Highpass on/off
1/9: Beeper
2/9: Serial Interf.
3/9: Ethernet
6/9: Instrument name
5/9: Factory setup
7/9: Load defaults
8/9: Overload limits
4/9: IEPE on/off
(password protected)
9/9: Firmware update
Figure 2: Display in measuring mode
Transducer sensitivity
Displayed
channel
Measuring value
Physical unit
Display mode RMS
Rel. magnitude
Press OK to stop
channel rotation
Press OK for channel rotation
High pass and low pass filter
Relay output
Display mode Peak
Rel. magnitude
below 5 % of full scale

3. What is IEPE?
The M208A is a signal conditioner for sensors with IEPE output. The abbreviation
stands for Integrated Electronics Piezo Electric and is a common industrial standard
for the output of piezoelectric sensors and microphones. Proprietary brand names,
like ICP®, Isotron®, Deltatron®, Piezotron® etc., are also used for the same purpose.
An electronic circuit inside the sensor transforms the high-impedance signal of the
sensing element into an output signal with low impedance, which can more easily
be transmitted and processed.
A distinctive feature of IEPE is the transmission of supply current and measuring
signal via one single wire, so an IEPE transducer is connected via a coaxial cable.
3 shows the principle circuit of an IEPE measuring chain. To supply the sensor elec-
tronics, constant current is used (not to be confused with -20 mA current loops).
The constant current is fed into the signal cable by the signal conditioner. A cou -
pling capacitor keeps the DC components away from the AC signal path.
When constant current is fed into the sensor, a positive DC voltage, called bias volt-
age, arises at the sensor terminals. Depending on model and manufacturer, the bias
voltage can be in the range from 5 to 1 V. The bias voltage is modulated with the
measuring signal usensor. The sensor output can never become negative. The mini-
mum output voltage is approximately 1 V, the saturation voltage of the sensor out-
put stage. The upper voltage limit is determined by the supply voltage of the con-
stant current source, also called compliance voltage. The M208A uses 2 V.
shows the dynamic range of an IEPE transducer.
7
Figure 3: IEPE principle
Integated electronics
U = 24VDC
I
= 4mA
const
s
QU
Sensing element
I
const
Constant supply current
U
s
Supply voltage of constant current source
Coaxial cable
> 1 m
IEPE Sensor M208
U
bias
+u
sensor
LED
sensor
indication
Filter
Amplifier Buffer
eadout unit
- 6 dB

The M208A features a circuit for sensor check. It can detect the following condi-
tions, based on the sensor output voltage:
•No sensor present (yellow LED off, no measuring value for this channel)
•Sensor detected (yellow LED on, measuring value displayed)
•Short circuit at input (display “IEPE SHORT”)
The constant current supply can be switched off for each channel (see section 12. .
on page 31). The sensor detection will then also be deactivated.
4. What is TEDS?
The M208A includes full TEDS support.
The abbreviation TEDS stands for “Transducer Electronic Data Sheet”. It specifies
sensors containing a memory device holding their most important characteristics.
An advantage of TEDS is that these characteristics are associated with the sensor
and cannot get lost. The measuring system can configure itself without entering any
data manually after the sensor being plugged in.
IEEE 1 51 describes the memory, the interface and the arrangement of data. In part
of this standard a sub-group of TEDS transducers is described which is compati-
ble with IEPE inputs. The memory can be accessed via the signal cable by means of
a negative logical pulse chain. When these sensors are supplied by constant current,
they perform like normal IEPE sensors. 5 shows the principle of TEDS.
8
Figure : Dynamic range of IEPE sensors
Max. sensor output =
supply voltage of constant current source
(24 V with M2 8)
Sensor saturation voltage
(approx. 1 V)
Sensor bias voltage
(see data sheet)
negative overload
V
positive overload
Sensor dynamic range

TEDS sensors include a memory device DS2 30A with a so-called 1-Wire® inter-
face made by Dallas/Maxim. This memory is divided into a 6 bit ROM portion,
called application register, which may be programmed once, and a re-programmable
256 bit EEPROM portion.
The application register, called the basic TEDS, contains data stored by the manu-
facturer. This data cannot be edited. It includes:
•Manufacturer code
•Type identifier
•Version number
•Version letter
•Serial number
The EEPROM holds sensor data which may be edited for calibration purposes.
Type and arrangement of this data depends on the TEDS template used. Standard
templates are published on the IEEE server at http://standards.ieee.org/regauth/1 51
In addition there are proprietary manufacturer templates.
The M208A supports the standard template no. 25 for piezoelectric accelerometers
and force transducers and the template nos. 27 and 28 for measuring microphones.
These templates allow the specification with or without a transfer function by means
of switch bits.
9
Figure 5: TEDS principle
U
I
const
s
C
k
Coaxial cable
IEPE Sensor with TEDS to IEEE 1451.4
Signal
conditioning
TEDS
Memory
Ampl.
TEDS
read / write
interface
- Manufacturer
- Model
- Version
- Serial number
- Sensitivity
- Direction, polarity
- Weight
- Frequency range
- Amplitude linearity
- Temperature coefficient
Sensing
element
IEPE
supply
- User text
- Measuring ID
Written only
by the
manufacturer
Written by the
manufacturer
and calibration
labs
Written by the
user

Template No. 25 for piezoelectric accelerometers and force transducers:
Without transfer function: With transfer function:
•Sensitivity
•Lower frequency limit
•Measuring direction
•Weight
•Polarity
•Calibration frequency
•Calibration temperature
•Calibration date
•Calibration initials
•Calibration interval
•ID of measuring point
•User text
•Sensitivity
•Lower frequency limit
•Measuring direction
•Weight
•Polarity
•Low pass frequency
•Resonance frequency
•Resonance quality
•Amplitude slope
•Temperature coefficient
•Calibration frequency
•Calibration temperature
•Calibration date
•Calibration initials
•Calibration interval
•ID of measuring point
•User text
Template No. 27 for measuring microphones:
Without transfer function: With transfer function:
•Sensitivity
•Reference frequency
•Reference polarization voltage
•Microphone type
•Microphone size
•Equivalent volume
•Polarity
•Calibration date
•Calibration initials
•Calibration interval
•ID of measuring point
•User text
•Sensitivity
•Reference frequency
•Reference polarization voltage
•Microphone type
•Microphone size
•Equivalent volume
•Actuator / correction
•High pass frequency
•Resonance frequency
•Resonance quality
•Polarity
•Calibration date
•Calibration initials
•Calibration interval
•ID of measuring point
•User text
10