Looks like you are getting an echo back. Try sending this packet in hex, "01 03 A0 30 00 01 crc". You should get the following packet back, "01 03 04 00 XX 00 00 crc" Where XX is 00 or 01 for stop, 02 for forward and 03 for reverse. You should be able to manually set the drive to forward and/or reverse and see this value change when you read again. What brand and model of 485 adapter are you using?
Iam getting an echo back, when i sent the last data packet the drive returns with the same info sent. The converter iam using is from http://www.rs485.com/pdffiles/converters/ssac44l.pdf, Since the 485 is only 2 wire from the drive i have placed jumpers for the converter.
You should have TX- and RX- tied together and to pin B on the drive then TX+ and RX+ tied together and to pin A on the drive. Also COM to pin G on the drive.
Just curious how you found out what register 41008 did, i can't find any documentation from register 41000 to 49999. Also how do you read the 32 bit data coming out from the holding registers
If you look at the end of the holding register table (table 10) registers 41000 - 49999 are actually the parameters. In the back of your drive manual is a table with all the parameters. "Unclebump" is right in that MODBUS only supports 16bit data that is why each parameter is two bytes worth of data. The trick is the first byte received is the LO byte. To get floating point you combine the two bytes and send through type cast with SINGLE as the 'type'.
