Author Topic: Modbus VB  (Read 5787 times)

hosana

  • Guest
Modbus VB
« on: April 08, 2005, 05:32:31 PM »
Dear all,

I have download the VB Modbus RTU Master Projects and Modbus Tester to try these software to my Twido PLC. When i try the VB Modbus RTU Master Projects there still an error while i push the read register button to read datas that came from my twido PLC, i also try the read single and it give result 63 for textbox1 to textbox 6 and .747058 for textbox16(it\'s different with the data that i send from the Twido PLC).So i use the Modbus tester to read the data and it give good result, the datas that i received are the same with datas that i send from PLC + 2 strange hexadecimal number (i think it\'s the CRC). is that right??can somebody help me to read datas using VB??

Next step i try to write the datas to twido PLC using VB Modbus RTU Master Projects but it give no effect on my twido PLC. can somebody give a suggestion about this??

thanks...

best regards,
hosana

chibale

  • Guest
Modbus VB
« Reply #1 on: May 06, 2005, 02:40:05 PM »
ť Dear all,
ť
ť I have download the VB Modbus RTU Master Projects and Modbus Tester to try
ť these software to my Twido PLC. When i try the VB Modbus RTU Master
ť Projects there still an error while i push the read register button to
ť read datas that came from my twido PLC, i also try the read single and it
ť give result 63 for textbox1 to textbox 6 and .747058 for textbox16(it\'s
ť different with the data that i send from the Twido PLC).So i use the
ť Modbus tester to read the data and it give good result, the datas that i
ť received are the same with datas that i send from PLC + 2 strange
ť hexadecimal number (i think it\'s the CRC). is that right??can somebody
ť help me to read datas using VB??
ť
ť Next step i try to write the datas to twido PLC using VB Modbus RTU Master
ť Projects but it give no effect on my twido PLC. can somebody give a
ť suggestion about this??
ť
ť thanks...
ť
ť best regards,
ť hosana

chibale sankey

  • Guest
Modbus VB
« Reply #2 on: May 06, 2005, 02:44:19 PM »
ť ť dear all

i am doing a project that concerns creating a VB interface that will send programs files to the twido PLC.

i want to know how to write the ascii modbus protocol.

does any one know what command words that can set the twido PLC in either run or stop mode.

ť thanks...
ť
ť best regards,
ť sankey

Innocenzo

  • Guest
Modbus VB
« Reply #3 on: June 07, 2005, 11:49:25 AM »
You must download this document PI_MBUS_300.pdf.
It explains the format of messages in modbus protocol.

Ciao,
Innocenzo:-)

lucy

  • Guest
Modbus VB
« Reply #4 on: June 15, 2006, 11:17:23 AM »
Please go to win tech website and download the master ans slave vb code. I have tested and it works fine. Do set the slave address to 1, baud rate 19200, Parity =8 and stopbit 1. You need to do some minor modification on the software as the initial setting is 9600

Lucy

Daniel Santoso

  • Guest
Modbus VB
« Reply #5 on: August 25, 2006, 09:37:09 AM »
I am a Modbus beginner and I need to calculate the CRC for a modbus command to a slave. The CRC examples I found are not very clear to me and they seem to conflict with each other.

1. Can you give a hint where to find a good and valid example how to calculate CRC, preferably in Visual Basic?