Response to Maik - Nov 3, 2014
@Maik, the reason slave address 0 is treated as broadcast is because this is defined by the Modbus protocol. This has nothing to do with the driver itself. If either of us had to write a Modbus driver, we would have to do the same just so we comply with the Modbus protocol.
- Oct 16, 2013
I'm trying to run the example of the
Ethernet Modbus feature. I created a *.vi
containing only 'MB Ethernet Example
Slave.vi' and another one containing only
'MB Ethernet Example Master.vi'. I run the
slave and the Master afterwards. After
some seconds, I get this message :
I use LabVIEW 8.5.1. Is this version
covered by this toolbox?
Very buggy - Oct 9, 2013
1. The Init VI handles all COM ports as
true COM ports, but it does not work with
VCOM. So I had to modify the serial
settings init (first Visa Open, then Visa
Serial Settings, not via property node)
2. There is no timing between Write and
3. Slave address 0 is considered as
broadcast in the sub VIs, but this applies
only for a serial line Modbus, which COM
ports and Ethernet are not, because
they're peer-to-peer. So the slave
address 0 detection in the sub VIs is
nonsense, because you can not make a
broadcast with slave address 0 on P2P.
- Sep 30, 2013
Hi I have the LabVIEW Run-Time 8.5
installed. I do not undersand how to install
the Modbus. In the help it says I should
copy the Modbus.llb to the
LabVIEW_ROOT\vi.lib folder. But I have no
such folder. Please help me
Compatibility with LabVIEW 8.6 and LabVIEW 2011 - Sep 20, 2013
Would you be able to tell me which of the
versions available are compatible with
And the same for LabVIEW 2011 ?
New and improved - Jul 15, 2013
Use the new modbus library on NI labs
instead of this one:
LabView 2011 - Jun 18, 2013
Does this lib work with version 11?
Thanks for any help.
- Apr 22, 2013
Please support this idea :
MB Update Registers bug... - Mar 8, 2013
I'll preface my remarks with some words
from Forrest Gump... "I'm not a smart
man...". But it appears that I've stumbled
across a problem with the MB Update
Registers subVI. Specifically for the
Function Code 1 and 2 (Read Coils and
Read Discrete Inputs) case.
The first three cases (i.e. the check
quantity, check quantity and start
address, and read coils/discrete inputs)
all work correctly. But the 4th case (the
encode booleans as U8) incorrectly
encodes the data. The While Loop
takes in the Bits Out array from previous
case and splits it into two parts. On the
first iteration, the Bits Out array is split at
index 8 and the first subarray is 8 bits
and gets encoded correctly as a U8,
while the second subarray is passed to
the next iteration of the loop. However,
on the second iteration of the loop,
the "new" Bits Out array being
processed (the original Bits Out with the
first 8 bits already removed) is split at
index 16. And while for the second
iteration of the loop this still returns a
correct encoding of the second 8 bits of
Bits Out (via truncating) array,
subsequent iterations will not be correct
because data gets lost.
The easy fix is to ALWAYS index the split
array function at 8 rather than tying it to
the iteration terminal. Or you could
replace the split array function with the
array subset function, tying index to the
iteration terminal as it is and setting the
length to ALWAYS be 8, and NOT use
shift registers at all.
Well, that's what I've come up with
anyway... but I'm not a smart man! :-)
Modify Stop bits in - Nov 14, 2012
I was able to make the library work in ASCII mode by making changes to "MB Serial Init.vi".
The "Stop bits" are set to 2, in ASCII mode and "STOP bits" as 1 in RTU mode. My application needs none parity.
Please see page 16 of the following ModBus spec http://modbus.org/docs/Modbus_over_serial_line_V1_02.pdf , for clarifications on ASCII mode.
ModBus on the LVTN - Sep 24, 2012
As an alternative to this "old" free
example provided by NI, 2 toolkits are
available to purchase on the LVTN.
For TCP -->
For Serial -->
SAPHIR have been developing and
maintaining these toolkits since LV 3.1.
Feel free to try them for free during 30
More information and support here -->
Modbus updates 2011 ??? - Aug 3, 2012
What's the status on Modbus ??? Is someone
from NI available to answer???
Modbus Library Updates? - Apr 11, 2012
When will I get NI Modbus libraries running
with LabVIEW 2010? I can not install
Labview 8.6 for it. Is there any alternative
solution to get this
Any updated code here? - Dec 30, 2011
has there been any investigation by NI about
the numerous bugs reported by users?
Have these libraries been updated?
Is there one complete, verified list of fixes
to this library anywhere?
- Oct 26, 2011
Th ASCII mode seems to be broken - no
chance to get it running in Labview 2011 -
while the RTU mode performs well ...
This is kind of poort ...
Bug in ASCII mode - Oct 9, 2011
Bug1: In "MB Serial String to Modbus
Data Unit", in the if structure, "x-9" should
be changed to "x-7".
Bug2: In "MB Decode Data", in the case
structure (3,4) , should delete "Array
Modbus Library Buggy - No real alternative - Nov 19, 2010
NI asks us to use the "LabVIEW
Datalogging and Supervisory Control
Module" for professional ModBus
support in LabView. Due to the run time
licensing scheme where you need a
DSC Runtime License that binds the
software to ONE computer, this is not an
alternative for our 24*7 customers. They
must be able to swap a PC with a new in
midst prodction if necessary.
Version 1.2.1 still as the CRC 16 bug in
MB CRC-16.vi as pointed out by "Jim
Figucia, Code G Automation" September
This very error haunted us with random
data: We just saw Jim's comment, and
fixed the bug in the VI.
Isn't it about time to fix the reported bugs
in this library?
- Nov 18, 2010
NI Says <<Please note that this is an example
program and not an official NI Product. For
a more complete, fully supported MODBUS
solution, NI recommends the LabVIEW
Datalogging and Supervisory Control Module. >>
That would have been fine: We own the DSC
Modul. However, the LICENSING binds the
deployed code to one Computer.
This is NOT Acceptable in a 24*7 environment
where we deploy all our systems: The customer
must be able to change the PC in mid
production it it breaks down.
Thus, we also had to resort to the buggy
Modbus Library. 1.2.1 still has the bug in
MB CRC-16.vi that casts a 16 Bit CRC to an U8 !
This was pointed out by "Jim Figucia, Code G
Automation. email@example.com - Sep 15,
2009" and is STILL NOT FIXED.
Error in 'MB Serial Init.vi' - Oct 25, 2010
Error in 'MB Serial Init.vi'
Modbus spec clearly states that if no
parity checking is used, 'stop bits'
should be set to '2'. This vi always sets
stop bits to '1'.
What about Labview 2009? - Aug 25, 2010
Hey is this going to work with labview 2009
too? I tried using the 8.6 version but i am
MODBUS - Jul 26, 2010
This Library didn't support MB Serial
Slave Demon.vi at Windows CE5.0 in
Touch panel Module.
library modbus 6.0 - May 29, 2010
Hello i'm looking for modbus library for
labview 6.0. i have the library for labview
6.1 but i can't open it with labview 6.0
MB Registers Manager.vi - Dec 8, 2009
Thanx for version 121 of this free library.
Is bug in "MB Registers Manager.vi" reported
Apr 29, 2009 fixed?
a flaw in MB CRC-16.vi in NI Modbus.llb - Sep 15, 2009
A failure mode turn up in testing at 1200
baud. It turned out to be a flaw in MB
CRC-16.vi in NI Modbus.llb.
The failure mode is that the MB Serial
Recieve.vi that waits for a Modbus reply
to a command may falsely detemines
that the message is complete before the
last byte is recieved. This is becuase
because MB CRC-16.vi coerces the U16
CRC to a U8, and the U8 becomes zero
for a message with all but the last byte
The correction is to change the data type
of the Exception Code indicator from U8
inform us and correct this in Library! - Apr 29, 2009
"The 'MB Registers Manager.VI' is used as the
repository for the Slave registers. In the
case of Write, however, the Start Address is
not being taken into account (compare this
with the Read cases to know what I mean). The
Start Address defaults to 0, always! The fix
is to wire-in the Start Address to the Index
input of the Array Subset primitive. This
alongwith the (already present) Length input
should write to the correct set of registers,
reported by Khalid - March 18, 2006
- Apr 16, 2009
thx for improving the library
The Modbus Slave implementation in this
library is buggy since 2006.
For Details see
Support for TPC targets LV8.51 - Mar 11, 2009
1. Can I use this library on a TPC-2106
target (Touch Panel Module project)?
When I try, not all of the example VIs are
executable - e.g. "MB Serial Wait on
Query" displays Target Specific Errors.
2. Copied, as instructed, lvmodbus.chm
and lvmodbus.txt from 85\help to the
LabVIEW_ROOT\help directory. The help
appears with the content seemingly
normal, but selecting any topic results
in: "This program cannot display the
ni_modbus8_2.exe file - Sep 4, 2008
want Maodbus toolkit for labview 7.0 .
plese give me a link or supply me
- Aug 21, 2008
Usually the LabVIEW libraries found on the NI
site are very helpful, well documented, and
intuitive. I'm not sure if it was just my
inexperience with the protocol or not, but
this has been the worst library I've
downloaded. There is next to no
documentation at all. Errors are not defined
and the examples not as helpful as could be
I'm having probles to use the library to read/write registers from a GE PLC, Any example? - Jun 30, 2008
automation - Jun 5, 2008
I want Maodbus toolkit for labview 7.0 ?
plese give me a link or supply me
- Feb 26, 2008
please tell me can i use this driver with
Modbus for LV 7.0 - Dec 28, 2007
Hello is there a serial port Modbus driver
for LV 7.0?
Zipped llb, please?! - Dec 4, 2007
please supply this as a cross-platform archive!
- Mar 26, 2007
i'm using labview 7.1
is there a version for this? or i use the 6.1
- Feb 1, 2007
Is there the Modbus Library for labview
Modbus for CVI - Nov 22, 2006
Is there CVI modebus function panel
why an MSI file????? - Oct 18, 2006
This is just a pain to the non-windows community. Who is
out there just being lazy or not-thinking.
LV 6.1 version - Apr 27, 2006
Here's the 6.1 version of this:
Modbus Slave is buggy - Mar 18, 2006
Modbus Slave implementation has a bug. See
this for details:
Why an .msi, not .llb?! - Feb 24, 2006
No use to us original (Mac) LabVIEW users; what am I
supposed to do with a Windows installer?! Isn't LV still a
cross platform language, born on the Mac?
Error in code - Feb 21, 2006
The "MB Modbus Command to Data Unit.vi" has
a mistake in it. The "Write Multiple Coils"
Function Code will not work properly past 8
bits of data. In case "15", the index to
the "Split Array" VI should just be 8.
Either that or you could remove the shift
register and use an index array instead.
The current implementation however corrupts
the output data past 8 bits.
Here's how to install this in LabVIEW 8.0 ... - Jan 6, 2006
When will it work with Labview 8.0??? - Nov 30, 2005
When will it work with Labview 8.0???
The german support team has told me that it
must work, but it doesn't!
After telling them that it doesn't work and
asking for a call back I got no answer until now!
versjon 8.0 - Nov 10, 2005
When will these libraries be available for
Compatable with Version 8 LABVIEW? - Nov 3, 2005
I was unable to run this Modbus Libuary
using the LABVIEW 8. I am currently trying
to concude that LABVIEW can talk Modbus and
how hard is it to configure to do this.
Several VIs display broken wires when compiled to LV8 - Nov 1, 2005
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