FISCHER DE43 User manual

Modbus
Operating manual
DE43
Digital 2-channel transmitter
for direct connection to
bus-capable automation devices
09005642 • BA_EN_DE43 • Rev. ST4-A • 11/18 *09005642*

| Impressum FISCHER Mess- und Regeltechnik GmbH
2 / 28 BA_EN_DE43
Impressum
Manufacturer: FISCHER Mess- und Regeltechnik GmbH
Bielefelderstr. 37a
D-32107 Bad Salzuflen
Telephone: [phone]
Telefax: [phone]
eMail: [email protected]
web: www.fischermesstechnik.de
Technical editorial team: Documentation representative: T. Malischewski
Technical editor: R. Kleemann
All rights, also those to the translation, reserved. No part of this document may
be reproduced or processed, duplicated or distributed using electronic systems
or any other form (print, photocopy, microfilm or another process) without the
written consent of the company FISCHER Mess- und Regeltechnik GmbH, Bad
Salzuflen.
Reproduction for internal use is expressly allowed.
Brand names and procedures are used for information purposes only and do
not take the respective patent situation into account. Great care was taken
when compiling the texts and illustrations; Nevertheless, errors cannot be ruled
out. The company FISCHER Mess- und Regeltechnik GmbH will not accept any
legal responsibility or liability for this.
Subject to technical amendments.
© FISCHER Mess- und Regeltechnik 2018
Version history
Rev. ST4-A 11/18 Version 1 (first edition)

FISCHER Mess- und Regeltechnik GmbH Table of contents
BA_EN_DE43 3 / 28
Table of contents
1 Safety instructions .........................................................................................................................................4
1.1 General .....................................................................................................................................................4
1.2 Personnel Qualification.............................................................................................................................4
1.3 Risks due to Non-Observance of Safety Instructions ...............................................................................4
1.4 Safety Instructions for the Operating Company and the Operator............................................................4
1.5 Unauthorised Modification ........................................................................................................................4
1.6 Inadmissible Modes of Operation .............................................................................................................4
1.7 Safe working practices for maintenance and installation work .................................................................5
1.8 Pictogram explanation ..............................................................................................................................5
2 Product and functional description ..............................................................................................................6
2.1 Delivery scope ..........................................................................................................................................6
2.2 Equipment versions ..................................................................................................................................6
2.3 Function diagram ......................................................................................................................................8
2.4 Design and mode of operation..................................................................................................................8
2.5 Intended use .............................................................................................................................................8
3 Assembly.........................................................................................................................................................9
3.1 General .....................................................................................................................................................9
3.2 Process connection ..................................................................................................................................9
3.3 Electrical connections .............................................................................................................................10
4 Start-up..........................................................................................................................................................13
4.1 Generalities.............................................................................................................................................13
4.2 Config select ...........................................................................................................................................13
4.3 Modbus functional description ................................................................................................................15
4.4 LED flash codes......................................................................................................................................21
5 Servicing .......................................................................................................................................................22
5.1 Maintenance ...........................................................................................................................................22
5.2 Transport ................................................................................................................................................22
5.3 Service....................................................................................................................................................22
5.4 Disposal ..................................................................................................................................................22
6 Technical data...............................................................................................................................................23
6.1 General ...................................................................................................................................................23
6.2 Input variables ........................................................................................................................................23
6.3 Communication parameter .....................................................................................................................23
6.4 Auxiliary energy ......................................................................................................................................24
6.5 Operating conditions...............................................................................................................................24
6.6 Construction design ................................................................................................................................24
7 Order codes ..................................................................................................................................................26
8 Attachments..................................................................................................................................................28

1 | Safety instructions FISCHER Mess- und Regeltechnik GmbH
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1 Safety instructions
1.1 General
This operating manual is an integral part of the product and therefore needs to
be kept close to the instrument in a place that is accessible at all times to the re-
sponsible personnel.
The following sections, in particular instructions about the assembly, commis-
sioning and maintenance, contain important information, non-observance of
which could pose a threat to humans, animals, the environment and property.
The instrument described in these operating instructions is designed and manu-
factured in line with the state of the art and good engineering practice.
1.2 Personnel Qualification
The instrument may only be installed and commissioned by specialized person-
nel familiar with the installation, commissioning and operation of this product.
Specialized personnel are persons who can assess the work they have been
assigned and recognize potential dangers by virtue of their specialized training,
their skills and experience and their knowledge of the pertinent standards.
1.3 Risks due to Non-Observance of Safety Instructions
Non-observance of these safety instructions, the intended use of the device or
the limit values given in the technical specifications can be hazardous or cause
harm to persons, the environment or the plant itself.
The supplier of the equipment will not be liable for damage claims if this should
happen.
1.4 Safety Instructions for the Operating Company and the Operator
The safety instructions governing correct operation of theinstrument must be
observed. The operating company must make them available to the installation,
maintenance, inspection and operating personnel.
Dangers arising from electrical components, energy discharged by the medium,
escaping medium and incorrect installation of the device must be eliminated.
See the information in the applicable national and international regulations.
Please observe the information about certification and approvals in the Tech-
nical Data section.
1.5 Unauthorised Modification
Modifications of or other technical alterations to the instrument by the customer
are not permitted. This also applies to replacement parts. Only the manufacturer
is authorised to make any modifications or changes.
1.6 Inadmissible Modes of Operation
The operational safety of this instrument can only be guaranteed if it is used as
intended. The instrument model must be suitable for the medium used in the
system. The limit values given in the technical data may not be exceeded.
The manufacturer is not liable for damage resulting from improper or incorrect
use.

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1.7 Safe working practices for maintenance and installation work
The safety instructions given in this operating manual, any nationally applicable
regulations on accident prevention and any of the operating company's internal
work, operating and safety guidelines must be observed.
The operating company is responsible for ensuring that all required mainten-
ance, inspection and installation work is carried out by qualified specialized per-
sonnel.
1.8 Pictogram explanation
DANGER
Type and source of danger
This indicates a direct dangerous situation that could lead to death or serious
injury (highest danger level).
a) Avoid danger by observing the valid safety regulations.
WARNING
Type and source of danger
This indicates a potentially dangerous situation that could lead to death or ser-
ious injury (medium danger level).
a) Avoid danger by observing the valid safety regulations.
CAUTION
Type and source of danger
This indicates a potentially dangerous situation that could lead to slight or seri-
ous injury, damage or environmental pollution (low danger level).
a) Avoid danger by observing the valid safety regulations.
NOTICE
Note / advice
This indicates useful information of advice for efficient and smooth operation.

2 | Product and functional description FISCHER Mess- und Regeltechnik GmbH
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2 Product and functional description
2.1 Delivery scope
• DE43 digital 2-channel transmitter
• Operating Manual
2.2 Equipment versions
Assembly
Attachment boreholes for tapping screws Wall mounting plate
Fig.1: Wall mounting
Item no.
Silicone-free
Measuring range
Measuring range
Ub
Interface
Prod. No..
Δ P1
Δ P2
DE435554P6M92MMW
0 ... 1600 Pa
0 ... 1000 Pa
24 V DC
RS 485
1808689.04.004
Silicone-free
Item no.
Measuring range
Measuring range
Ub
Interface
Prod. No.
DE435455P6L92MMW
0 ... 1000 Pa
0 ... 1600 Pa
24 V DC
RS 485
1808689.04.005
Δ P1
Δ P2
Standard version 90° rotated
Attention!Do not disconnect from the mains
or open the case while energized.
Attention!Do not disconnect from the
mains or open the case while energized.
Fig.2: Type plate
Process connection
Aluminium CK screw connection
for 6/4 or 8/6 mm hose
Pneumatic plug connection
for 6/4 or 8/6 mm hose
P1
++
P2
Fig.3: Process connection

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Electrical connections
M12 Plug 1
(male)
M12 Plug 2
(female)
2 1
3 4
5
A
1 2
4 3
5
A
2 Digital inputs (3,4) left 4 Digital inputs (1...4) 2 Digital inputs (1,2) right
E1
E2
E3
E4
E1
E2
E4
E3
1
4
3
M8 Bush
(female)
Fig.4: Electrical connections
2.2.1 Type plate
The presented type plates serve to show an example of the information shown.
The data shown is purely fictive, but does correspond to the actual conditions.
For more information, please see the order code at the end of these instruc-
tions.
Item no.
Silicone-free
Measuring range
Measuring range
Ub
Interface
Prod. No..
Δ P1
Δ P2
DE435554P6M92MMW
0 ... 1600 Pa
0 ... 1000 Pa
24 V DC
RS 485
1808689.04.004
Silicone-free
Item no.
Measuring range
Measuring range
Ub
Interface
Prod. No.
DE435455P6L92MMW
0 ... 1000 Pa
0 ... 1600 Pa
24 V DC
RS 485
1808689.04.005
Δ P1
Δ P2
Horizontal
Vertical
Order code
Techn. Data
Serial number
Fig.5: Type plate

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2.3 Function diagram
DIP
µC
D
A
D
A
E1
E2
E3
E4
BUS
POWER
+
+
P1
P2 2
Input 1
Input 2
Input 3
Input 4
1 Modbus IN
Modbus OUT
1
2
34
5
6
7
Fig.6: Function diagram
1 Sensor element 2 Micro-controller
3 AD converter 4 Digital inputs
5 Modbus interface 6 Power Supply
7 Modbus configuration
2.4 Design and mode of operation
The basis of the DE43 transmitter comprises two piezoresistive sensor ele-
ments.
The pressure that is to be measured acts upon a silicone membrane that is
equipped with a resistor bridge. The acting pressure causes the membrane to
move and therefore a change in resistance. The bridge signal is analysed by
the integrated electronics and converted to a pressure value.
The DE43 transmitter communicates with an overriding control system via an
RS 485 interface and a Modbus RTU protocol. The currently measured value is
forwarded by the overriding control system on request.
The device also has a connecting slot for two or four proximity switches whose
signals can also be queried through the Modbus by the overriding control sys-
tem.
2.5 Intended use
The digital 2-channel transmitter DE43 is suitable for measuring pressure, un-
der-pressure, and differential pressure in neutral gaseous media. The measured
value is transferred to an overriding control system via an RS 485 interface with
a Modbus RTU protocol.
Optionally, the device can monitor up to four external potential-free contacts,
and send their switching status to the overriding control system.

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3 Assembly
3.1 General
The device is designed for installation onto flat assembly plates. For screw con-
nection to the assembly plate, the device features four assembly bores on its
back, which can be used for Ø 3.5 mm tapping screws.
Optionally, the device can be delivered with a wall-mounting plate. This is also
available as accessory.
At the factory, the device is calibrated for vertical installation, but the installation
position is arbitrary.
The enclosure protection type IP 65 is only guaranteed, if a suitable power sup-
ply cable is used (see accessories).
If the device is intended for outdoor use, we recommend permanent protection
against against constant rain or snow, however at the least a sufficiently dimen-
sioned canopy.
3.2 Process connection
• By authorized and qualified specialized personnel only.
• The pipes need to be depressurized when the instrument is being connec-
ted.
• Appropriate steps must be taken to protect the device from pressure surges.
• Check that the device is suitable for the medium being measured.
• Maximum pressures must be observed (cf. Tech. data)
The pressure lines must be installed on a gradient so that no water pockets for
gas measurements can be created. If the required gradient is not reached, wa-
ter filters need to be installed at suitable points.
The pressure lines must be kept as short as possible and installed without any
tight bends to avoid delays.
The process connections are marked with (+) and (-) symbols on the device.
The pressure lines must be mounted according to these symbols.
CK Screw connection Pneumatic Plug connection
Channel 2Channel1
+ +
Channel 2Channel1
+ +
Differential pressure Pressure Under-pressure
+higher pressure
lower pressure
+Pressure
open
+open
Under-pressure
Fig.7: Process connection
The process connections are suitable for hoses made of various materials (PA,
PU, Teflon, etc.) with the following dimensions:
Process connection for Hose 8/6 Hose 6/4
Outer diameter 8 mm 6 mm
Inner diameter 6 mm 4 mm

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3.3 Electrical connections
• By authorized and qualified specialized personnel only.
• When connecting the unit, the national and international electro-technical
regulations must be observed.
• Disconnect the system from the mains, before electrically connecting the
device.
• Do not connect the connector if strained.
Plug 1
Plug 2
E1
E2
E3
E4
Access
Modbus configuration
Fig.8: Electrical connections
WARNING!Please note for the power supply to the devices that the M12
plugs are only suitable for max. 2A.
Plug 1 (Input)
Supply and bus connection
2 1
3 4
5
A
Fig.9: M12 connector 5-pin
PIN Signal name Cable colour
ACoding
1“Supply” dialogue +Ubbrown
2BUS-D1 white
3“Supply” dialogue -Ubblue
4BUS-D0 black
5BUS-R grey
Plug 2 (Output)
Supply and bus connection
1 2
4 3
5
A
Fig.10: M12 bush 5-pin
PIN Signal name Cable colour
ACoding
1“Supply” dialogue +Ubbrown
2BUS-D1 white
3“Supply” dialogue -Ubblue
4BUS-D0 black
5BUS-R grey
Digital inputs (E1 … E4)
Input for external potential-free contacts.
1
4
3
Fig.11: M8 bush
PIN Signal name Cable colour
1Supply contact 1 (+) +UE1 brown
3Supply contact 1 (-) -UE1 blue
4Input E1 black
The assignment of the M8 bushes is the same for all contacts, which is why
only the assignment of digital input E1 is shown here as a example.

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3.3.1 Modbus RTU network
The DE43 is usually connected in a line network structure as a so-called slave
to the Modbus RTU network. Up to 123 bus participants can be operated
without an amplifier on one strand
NOTICE!Star-shaped networks are not allowed.
MASTER DE43
1 2
DE43
1 2
DE43
1 2
Address 1 Address 2 Address 127
Bus termination
DC
AC
M
Feed
1 2E
Modbus 5
Fig.12: Modbus RTU network
Communication is effected solely via a Modbus master that is also connected to
the bus system. The connected slaves only react to direct commands from the
master, which is why communication between the slaves is not possible.
To guarantee fault-free data transmission, we recommend terminating the end
point of the Modbus RTU network with a 120Ω resistor. These bus terminating
resistors are available as accessories.
It can be connected to an existing Modbus network via a conventional T-piece
(passive TAP).
MASTER
M
TAP
M
Slave
TAP
LT LT
M
Slave
TAP
DE43
1 2
Supply
1 2E
DC
AC
Fig.13: Modbus connection

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Supply circuit
BUS-D1
BUS-D0
BUS-R
DC
AC
BUS-D1
BUS-D0
BUS-R
Ub +
Ub -
1
3
2
4
5
DE43 SlaveMaster
+
Fig.14: Supply
Please note that the M12 plugs are suitable for max. 2A. This value may
already be exceeded if there are more than 23 bus participants (without digital
inputs). For this reason, an intermediate feed should be provided at a suitable
place.
DE43
1 2
Address 24
DC
AC
2. Feed
1 2E
DE43
1 2
Address 23
Ub1
Ub2
3
2
5 5
Modbus
∑Ix< 2 A
x=1
k
Fig.15: Intermediate supply
Please note that a DE43 with digital inputs has a higher power draw. If the bus
participants are equipped with digital inputs, the number of possible bus parti-
cipants of a supply circuit are reduced.
The power draw of a device x with n digital inputs is calculated as follows: Ix =
55 mA + (n*4.5 mA)
This is calculated for the first bus participant and each of its successors. The
results are accumulated in sequence until the result exceeds the limit value 2 A.
The interim feed is then set after the bus participant k at which the total current
of the supply circuit last lay below 2 A.

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4 Start-up
4.1 Generalities
A prerequisite for commissioning is correct installation of all electrical supply
lines and the pressure lines. All connections are arranged so that there are no
mechanical forces acting on the device.
Also, know-how of the Modbus RTU protocol and the bus architecture are re-
quired to commission the bus system.
4.2 Config select
The DE43 Transmitter can be configured using an 8-digit DIP switch. To this
end, the sealing plug in the front plate needs to be removed. Below this is an 8-
pin DIP switch which can be used to configure both the Modbus address and
also the interface.
Sealing plug
Seal
DIP-switch
OFF
ON
Switch position
Fig.16: Access to the DIP switch
After all settings have been made, close the front plate with the plug. Always
use the original seal in this case. The sealing plug is screwed in tightly by hand.
4.2.1 Interfaces configuration
NOTICE!An X marks a random switch setting
S1 S2 S3 S4 S5 S6 S7 S8
Baudrate Parität
Stoppbit
XON
Fig.17: DIP switches
The switch S8 is used to select between the interface configuration and Modbus
address setting. For the interface configuration, ensure that the switch S8 is al-
ways in the setting ON.

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Baud rate S1 S2 S3 S4 S5 S6 S7 S8
1200 OFF OFF OFF X ON
2400 ON OFF OFF X ON
4800 ON ON OFF X ON
9600 OFF ON OFF X ON
19200 ON OFF ON X ON
38400 OFF OFF ON X ON
57600 ON ON ON X ON
Parity S1 S2 S3 S4 S5 S6 S7 S8
None OFF OFF X X ON
Identical parity ON OFF OFF XON
Not identical parity OFF ON OFF XON
It is not possible to combine identical or non-identical parity with 2 stopbits.
Stopbits S1 S2 S3 S4 S5 S6 S7 S8
1 stopbit OFF X ON
2 stopbits ON X ON
The device needs to be restarted to confirm the settings. To do this, disconnect
the device briefly from the power supply (plug 1).
4.2.2 Modbus address
To set the Modbus address, the switch S8 must be in the position OFF.
S1 S2 S3 S4 S5 S6 S7 S8
Modbus Address OFF
Fig.18: DIP switches
The address is entered in the dual system. The switches S1 to S7 represent the
respective setting value as follows:.
S1 S2 S3 S4 S5 S6 S7
Binary 20212223242526
Decimal 1 2 4 8 16 32 64
For example:
The Modbus address 24 should be set.
S1 S2 S3 S4 S5 S6 S7 S8
Switch set-
ting
OFF OFF OFF ON ON OFF OFF OFF
Priority 0*200*210*221*231*240*250*26
Total 0 +0 +0 +8 +16 +0 +0 =24
The device needs to be restarted to confirm the settings. To do this, disconnect
the device briefly from the power supply (plug 1).

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4.3 Modbus functional description
The following describes the Modbus functions that support the DE43 Transmit-
ter. The descriptions are initially kept general as explained in the Modbus Pro-
tocol Specification and are then supplemented with the unique features of the
DE43.
4.3.1 Modbus Transaction
A Modbus transaction comprises two parts. A request from the Master and a re-
sponse from the Slave.
Master Slave
Init Request
Function Code Data Request
Instruction executed
&
Modbus response
Receive Response
Function Code Data Response
Fig.19: Error-free request/response cycle
If an error occurs during a Modbus transaction, the Function Code is replaced
with a special Function Code with an error indicator in the Modbus Response
message and a more detailed description of the error in the data field is sent.
Master Slave
Init Request
Function Code Data Request
Error detected
&
Modbus response
Receive Response
Error CodeFunction Code (error)
Fig.20: Faulty request/response cycle
4.3.2 Modbus telegram
The maximum size of a Modbus telegram is 256Byte. The telegram comprises a
1 byte slave address, a 1 byte function code, the data and a 2byte CRC-check-
sum.
Frame 1
3.5 char 3.5 char
4.5 char
Frame 2
3.5 char
Frame 3
t0
Starting
≥3.5 char
Address
8 bit
Function
8 bit
Data
N x 8 bit
CRC Check
16 bits
End
≥3.5 char
Modbus message
Fig.21: Modbus Message Frame

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4.3.3 Function code 0x02: Read Discrete Inputs
This function code is used to read digital inputs.
Request The query contains the address of the first bits that are to be read and their
number.
0x02 MSB LSB MSB LSB
51 2 3 4Byte
Byte Field name Size Value range
1 Function Code 1 byte 0x02
2.3 Start Address 2 bytes 0x0000 to 0xFFFF
4.5 Number of inputs 2 bytes 1 to 2000 (0x7D0)
The DE43 can be equipped with up to four digital inputs.
Bit Data type Description State
0 Boolean Digital input 1 0 or 1
1 Boolean Digital input 2 0 or 1
2 Boolean Digital input 3 0 or 1
3 Boolean Digital input 4 0 or 1
Response The states of the digital inputs are summarised as bytes in the response. The
number of bytes (N) is the result of the number of inputs divided by 8. If there is
a rest, the number of bytes increases (N=N+1).
However, as the DE43 only has a maximum of 4 inputs, only 1 byte is trans-
ferred as a response.
The states of the digital inputs from the bit with the lowest value are saved
within a byte. A bit value of 0 corresponds to the status OFF; a bit value of 1
corresponds to the status ON.
0x02 N Byte1 Byte N
1 2 3Byte
...
Byte Field name Size Value range
1 Function Code 1 byte 0x02
2 Number of bytes 1 byte N
3… Number of inputs N Bytes 8 Bit value
Error
0x82 Code
1 2Byte
Byte Field name Size Value range
1 Function Code (error) 1 byte 0x82
2 Error code 1 byte Code s. table Error codes [}21]

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4.3.4 Function code 0x03: Read Holding Registers
This Function Code is used to read the Holding Register. The maximum pos-
sible number of registers that can be addressed in one message is 125.
Request The request contains the address of the first register that is to be read and the
number of registers that need to be read. The addressing of the register starts
with 0; the numbering of the registers starts with 1.
0x03 MSB LSB MSB LSB
51 2 3 4Byte
Byte Field name Size Value range
1 Function Code 1 byte 0x03
2.3 Start Address 2 bytes 0x0000 to 0xFFFF
4.5 Number of registers 2 bytes 0x0001 to 0x007D (1…125)
The DE43 Transmitter has precisely 1 Holding Register with the address
0x0000.
Bit Data type Description State
0 Unsigned Integer Pressure sensor
1
Sensor error 0 or 1
1 Unsigned Integer Pressure sensor
1
Pressure too low 0 or 1
2 Unsigned Integer Pressure sensor
1
Pressure too high 0 or 1
3 Unsigned Integer RESERVED 0 or 1
4 Unsigned Integer Pressure sensor
2
Sensor error 0 or 1
5 Unsigned Integer Pressure sensor
2
Pressure too low 0 or 1
6 Unsigned Integer Pressure sensor
2
Pressure too high 0 or 1
7 Unsigned Integer RESERVED 0 or 1
8 Unsigned Integer Temp. sensor Sensor error 0 or 1
9 Unsigned Integer Temp. sensor Temperature too low 0 or 1
10 Unsigned Integer Temp. sensor Temperature too high 0 or 1
11 Unsigned Integer RESERVED 0 or 1
12 Unsigned Integer General System error 0 or 1
13 Unsigned Integer RESERVED 0 or 1
14 Unsigned Integer RESERVED 0 or 1
15 Unsigned Integer RESERVED 0 or 1
Response The response contains two bytes for each read register; therefore the number of
bytes is twice of the number of registers (N).
0x03 2N MSB
1 2 3Byte
...
4
LSB MSB LSB
Register 1 Register N
Byte Field name Size Value range
1 Function Code 1 byte 0x03
2 Number of bytes 2 bytes 2N
3.4 Holding Register N x 2 Byte 16 Bit value

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Error
0x83 Code
1 2Byte
Byte Field name Size Value range
1 Function Code (error) 1 byte 0x83
2 Error code 1 byte Code s. table Error codes [}21]
4.3.5 Function code 0x04: Read Input Register
This Function Code is used to read the input register. The maximum possible
number of registers that can be addressed in one message is 125.
Request The request contains the address of the first register that is to be read and the
number of registers that need to be read. The addressing of the register starts
with 0; the numbering of the registers starts with 1.
0x04 MSB LSB MSB LSB
51 2 3 4Byte
Byte Field name Size Value range
1 Function Code 1 byte 0x04
2.3 Start Address 2 bytes 0x0000 to 0xFFFF
4.5 Number of registers 2 bytes 0x0001 to 0x007D (1…125)
The DE43 Transmitter has 3 Input Registers.
Reg.No. Address Data type Description Unit Contents
1 0x0000 Integer Measured value channel
1
PA Measured
value
2 0x0001 Integer Measured value channel
2
PA Measured
value
3 0x0002 Integer Temperature measured
value
°C Measured
value
Response The response contains two bytes for each read register; therefore the number of
bytes is twice of the number of registers.
0x04 2N MSB
1 2 3Byte
...
4
LSB MSB LSB
Register 1 Register N
Byte Field name Size Value range
1 Function Code 1 byte 0x04
2 Number of bytes 2 bytes 2N
3.4 Content Register N x 2 Byte 16 Bit value
Error
0x84 Code
1 2Byte
Byte Size Value range
1 Function Code (error) 1 byte 0x84
2 Error code 1 byte Code s. table Error codes [}21]

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4.3.6 Function code 0x2B/0x0E: Device Identification
This Function Code is used to read certain information about identification of the
unit. The following object types are used in the FISCHER units:
Object ID Object Name Type Category
0x00 VendorName ASCII String Basic
0x01 ProductCode ASCII String Basic
0x02 MajorMinorRevision ASCII String Basic
0x03 VendorUrl ASCII String Regular
0x04 ProductName ASCII String Regular
0x05 ModelName ASCII String Regular
0x06 UserApplicationName ASCII String Regular
NOTICE!There are no objects of the Extended category.
Request
0x2B 0x0E DevID ObjID
1 2 3 4Byte
Byte Field name Size Value range
1 Function Code 1 byte 0x2B
2 MEI Type+) 1 byte 0x0E
3 Read Device ID Code 1 byte 01 / 02 / 04
4 Object ID 1 byte 0x00 to 0xFF
+) MEI = Modbus Encapsulated Interface
Read Device ID
The Read Device ID Code (DevID) serves to specify the access. If the code is
not correct, an error message with the code 0x03 is sent.
01 Access to objects of the Basic category stream access
02 Access to objects of the Regular category stream access
04 Access to a single object individual access
If the length of the requested information exceeds the maximum possible length
of the PDU, several transactions (Request/Response) must be carried out.
Object ID
The Object ID Code states on which object of the 'stream access‘ should start. If
the Object ID does not match the existing objects, the 'stream access‘ starts
with the first object of the category. In the event of an 'individual access‘, an er-
ror message is generated with the error code 0x02.

4 | Start-up FISCHER Mess- und Regeltechnik GmbH
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Response The response comprises several bytes with status information followed by a list
with the requested object information.
0x2B 0x0E DevID
1 2 3 4Byte
Conf
5
Follow
6
Num ObjID Len Val
1
ObjID Len Val
Object NObject 0
...
List
Val
k
Val
... ...
... 01 k ... N
Next
7
Byte Field name Size Value range
1 Function Code 1 byte 0x2B
2 MEI Type 1 byte 0x0E
3 Read Device ID Code 1 byte 01 / 02 / 03 / 04
4 Conformity Level 1 byte 0x83
5 More Follows 1 byte 0x00 / 0xFF
6 Next Object ID 1 byte Object ID Number
7 Number of Objects 1 byte
List of object data
Object(N).ID 1 byte
Object(N).Length 1 byte
Object(N).Value k Byte
Conformity Level
The Conformity Level specifies the information category and the access type
that is supported.
0x83 Extended Identification stream and individual access
More Follows
If the length of the requested information exceeds the maximum possible length
of the PDU, several transactions (Request/Response) must be carried out. The
'More Follows‘ byte signalises whether or not further requests are required to
transfer all information.
0x00 no further objects
0xFF other objects available other transaction necessary
Next Object ID
If a further transaction is required (More Follows = FF), the Object ID for the fol-
lowing Request is stated at this point.
Otherwise (More Follows = 00) this value is useless and is set to 00.
Number of Objects
This byte states the number N of the objects that are transferred in the re-
sponse. In the case of 'individual access‘ the number of objects is = 01.
List of object data
Object(0).ID Object ID of the first object in the response
Object(0).Length Length of the object
Object(0).Value Value of the object
…
Object(N).ID Object ID of the last object in the response
Object(N).Length Length of the object
Object(N).Value Value of the object