Frequentie controller problem.
Frequentie controller problem.
(OP)
I have a hitachi L200 frequentie controller.
The L200 has an modbus output on RJ-45 connector.
I would like to control the L200 with a C++ program.
I bought a RS232/RS485 convertor to make the conversion between my PC and the modbus.But I'am unable to connect the L200 with my PC it just doesn't respond.It always gives me an read error amd write error. I'am using a modbuspoll program that I found on the net.
The L200 has an modbus output on RJ-45 connector.
I would like to control the L200 with a C++ program.
I bought a RS232/RS485 convertor to make the conversion between my PC and the modbus.But I'am unable to connect the L200 with my PC it just doesn't respond.It always gives me an read error amd write error. I'am using a modbuspoll program that I found on the net.





RE: Frequentie controller problem.
Keith Cress
Flamin Systems, Inc.- <http://www.flaminsystems.com>
RE: Frequentie controller problem.
I'am using a rs485/rs232 from patton.
I did a loopback test with that, with the hyperterminal.
And thatworked as well.
I also checked to modbus at the company where I bought it,
and the modbus works with an HMI.
RE: Frequentie controller problem.
I guess you have the Hitachi L200 manual for communicating?
www
RE: Frequentie controller problem.
I used the same cable with the HMI and that worked.
I'am using model 2089 from patton as a RS485/RS232 converter. But that has XMT+;XMT-;RCV+;RCV- as connections.
I tried to connect XMT+;RCV+ together and XMT-;RCV- together and then the positive to SP and the negative to SN.
But that didn't work either
RE: Frequentie controller problem.
Going from a 4-wire to 2 wire may need 120ohm between TX+ and TX- to terminate.
I wonder if there is a parameter in the drive to determine if telegrams are being recieved. Not sure.
I'm no expert on Hitachi drives it's just that we test most drives here in our lab and I know we did look at the L200 and tested the Modbus RTU link a few years back (btw, it is RTU and not ASCII you are outputting?). It did work ok after we figured the pin connections.
RE: Frequentie controller problem.
I'am sure parameters A001;A002;A076 are set in a good way.
I use RTU. Here is the site from the program that I used
www.modbustools.com
RE: Frequentie controller problem.
RE: Frequentie controller problem.
It could be the way the converter is being controlled. The 485 transmitter needs to be turned on and off at the right times. It seems that converter requires hardware control and your scanning program possibly isn't doing this. I've always had good luck with B&B Electronics converters and have used the 485SD9TB converter many times. It does automatic transmitter control so you don't have to worry about doing it yourself. I've also used Modscan from www.win-tech.com with good luck.
RE: Frequentie controller problem.
OPE/485 dip switch is on 485
A001=03
A002=03
Barry1961
RE: Frequentie controller problem.
Thx for the reply anyway
RE: Frequentie controller problem.
If you keep insisting that everything is correct then we're naturally going to assume that everything is correct which means it must be working.
RE: Frequentie controller problem.
I don't get any respons from the drive.
If I send a command with the test center from that program I see the command that I send in the traffic. But I don't get any respons from the drive back.
I think it must have something to do that the L200 only has 2 ouput(send/receive pos,neg) and the input to my convertor is 4 inputs (transmit pos/neg;receive pos/neg).
RE: Frequentie controller problem.
Eng-Tips: Help for your job, not for your homework Read FAQ731-376
RE: Frequentie controller problem.
The converter says it will do RS422 or RS485 (2 or 4 wire). Usually, with this type of port, you connect the TX and RX connections together as you have done.
With RS485, you have to turn the transmitter of the sending device on to send the data and then back off to receive the response. As I posted before, I've used the B&B Electronics RS485 converters that have automatic transmitter control very successfully. On the other hand, I've had very mixed results with converters that require hardware transmitter control.