libmodbus on a Solar Inverter

[shaddow]

Hello

I am trying to get to read my Growatt Solar Inverter via my usb/rs232 /dev/cuaU1 port on FreeBSD 8.2-RELEASE amd64.

I have got libmodbus installed with no problems.

I have been working on a modified version of sunsavertest by Tom Rinehart.

But where I am coming stuck is trying to get "modbus_read_input_registers" to work.

I see things transmitting but I am not getting any data back

I have used (On WindowsXP)  modbuspoll, it sees the inverter on the com port,
speed 9600 Parity; None, Data; 8, Stop; one, Handshake; None
slave ID ; 1
Function; 04
Address; 1

I have in the script (main parts pasted).

modbus_t *ctx;
int rc;
uint16_t data[34];
ctx = modbus_new_rtu("/dev/cuaU1", 9600, 'N', 8, 1);
modbus_set_slave(ctx, 1);
rc = modbus_read_input_registers(ctx, 1, 4, data);

I have tried other settings in input_reg but no work :(

I am not a programer by trade so I am only going by other peoples examples.

I need it to read about 34 data points, and am going to get rrdtools & php to read it to create graphs.

BUT just getting it to read the input_registers would be great

Can some one help PLEASE.

[Stéphane Raimbault]

2012/6/21 shaddow <shaneh...@gmail.com>

Are you able to read something with modpoll?

Holding registers are more common than input registers.

Address 1 under modpoll is address 0 in libmodbus.

Stéphane 

[shaddow]

I have some screen dumps of modbus poll

Screen dump of "03 Read Holding Registers"
Settings

Screen dump 0f "04Read Input Registers"
Settings

After Alias are filled in Manually

Read Input Registers are "not Signed"

[Stephane Raimbault]

I don't think modpoll is able to display queries, you can use Wireshark (may be you need this http://wiki.wireshark.org/CaptureSetup/USB) to compare the queries of modpoll with the queries of libmodbus and understand why your device doesn't answer.

 

[shaddow]

The program I am using to give out the stats is "http://www.modbustools.com/modbus_poll.asp"  but that is on windows.

I need to get some thing to work of FreeBSD that is why I an trying to get libmodbus to work.

The machine I am using is a production machine so it can not run wireshark with out braking other things on the system.