MIAC - MODBUS

[SAutoMotive]

Good evening all,

Maybe a bit stupid question, but I am struggeling a bit with using the FC7 and a new dsPIC MIAC(without wireless/bluetooth).
Till now I was working with CANbus communication and that works very fine. (both standard and extended messages)

Now I want to communicate onto the RS232 with MODBUS RTU, but I cannot get this working...
MODBUS is quite new to me, I am working in the automotive world and there is everthing about CANbus, no MODBUS.
(hope that you will help me starting with this stuff...)

I am looking for a very simple example to get a MIAC communicating onto Modbus, both as slave and as master.
Have found the examples on the Flowcode Wiki, but I think I made some mistakes is setting up the communication, because I cannot find any data with my laptop onto the RS232 output of the MIAC.(using the CAS MODBUS scanner)

To be sure about the connections/jumpers inside the MIAC:
On page 11 of the datasheet is a picture of the jumpers inside, which one is correct for MODBUS on RS232?
http://www.matrixtsl.com/resources/file ... C-60-3.pdf

Connecting the RX, TX and GND is enough to get the MODBUS working, isn't it? I can't find a proper answer if I need the CTS and RTS also...

Thanks in advance!!

[LeighM]

Hi,
Yes, RTS/CTS are not used by the Modbus component, so the default link settings, giving RS232 and RS485 interfaces, should be used...

default_links.jpg (21.79 KiB) Viewed 8288 times

For RS232 use hardware UART(0) Channel 1 on Port E pins 0 and 1

rs232master.jpg (28.99 KiB) Viewed 8288 times

Hope that helps,
Leigh

[SAutoMotive]

Hi Leigh,

Thanks for your answer!
These settings are used in my test projects...

To be sure, which pin is used for the GND connection?
Just the normal GND of the MIAC or the 0R of the inputs, does this matter?

Could you give some advise in what kind of MODBUS logger/monitoring software works well?

[LeighM]

To be sure, which pin is used for the GND connection?
Just the normal GND of the MIAC or the 0R of the inputs, does this matter?

Use the normal GND (0R is for analog inputs ground)

Could you give some advise in what kind of MODBUS logger/monitoring software works well?

I've no recommendations on that, but I'm sure there are others on the forum that have

[EtsDriver]

I use mbpoll for debugging/logging modbus data.
http://www.modbustools.com/modbus_poll.html

[Steve001]

modscan is another

http://www.win-tech.com/html/modscan32.htm

steve

[SAutoMotive]

Hi Steve,

Thanks!

Yesterday I found this program and it was very useful!