Communication Protocol with RS485 and Yokogawa UP351

[PBY1]

Need help with yokogawa controller model UP-351.  I can talk to it via yokogawa-provided software parameter setting tool OK but not through NI Visa.  Any suggestions?

[PBY1]

Additional info: 

My system has three of these UP351 devices (addr. 01 through 03) and they are configured in (RS485) 2-wire mode.

I am using the same port settings as does the Yokogawa software (LL100 Param. Setting  Tool) and have verified they match settings on the controllers.

I am not receiving responses from the controllers when sending commands from Labview (via NI VISA) using the PC Link communication protocol described in the Yokogawa manual.

[Wayne.C]

Can you post a sample vi that shows how you are configuring the 485 port and sending the command?

[PBY1]

Attached you'll find a basic serial write/read version of the VI I have been trying to use. 

The command I have been attempting ("201010INF63/r) is intended to read the model, version, and revision information.  The command is supposedly broken down as follows:

2(STX)  01(ADR)  01(CPU# fixed)  0(time to wait for response - also fixed)  INF(Command)  6(Data corresponding to command - variable length; I believe I am telling the controller to return 6 bytes, which should at least provide model)  3(ETX) CR(/r).

I am not using checksum, and all commands/responses end with carriage return (/r)

When I run the VI, the controllers apparently ignore the command and it just sits at the port and is read back.

Thanks for your interest:)

Paul 

[Wayne.C]

Paul,

Based on experience with other Yokogawa instruments, I pretty sure that your command string is the problem.  The first thing to remember is that in "\" display mode, the STX character is entered as "\02".  ETX is entered as "\03".  I'm also pretty sure that the carriage return is sent before the ETX character.  Based on those changes and assuming that the rest of your command sytax is correct the string would be:

"\0201010INF6\r\03"

I am also sure that there are some spaces "\s" that also need to be in the string between the commands and the modifiers.  Can you post a copy of the serial com docs for this meter?

[PBY1]

Thanks for your input regarding the command structure.  I will try some variations as you described and refer again to the Communications Manual which I located through Yokogawa's support website (http://support.us.yokogawa.com/) Refer to section 3.1.

In some new developments I have learned there is an "Advanced" tab under Port Settings through Measurement & Automation where I can set the "Transceiver Mode":  There are four options: 4-Wire, 2-Wire controlled with echo, 2-Wire DTR controlled, and 2-Wire auto.  I know I am connected in 2-wire mode but I'm not well-versed in serial to be sure which option I should be using.  Depending upon which I have selected, my VI responds as described earlier or will generate a timeout error at the Visa Read.  Yokogawa's LL100 software will talk when using any of the settings except for 2-Wire DTR controlled.

Paul

[Wayne.C]

Paul,

Looked at manual.  Looks like you are using the PC Link communication scheme.  No spaces needed and the "\r" is indeed at the very end.   String should = "\0201010INF6\03\r" Amazing how many com schemes Yokogawa uses. 

I made a slight change to your vi.  I suggest that you start out adding the termination character to the string you write.  The termination character you were setting with the property node actually sets the receive termination character. 

I'm guessing that you should be using 2-Wire Auto.  What are you using for the 485 port on your PC?  That will have a lot to do with this.

[PBY1]

Success!  After verifying the port was set to 2-Wire Auto and using the command syntax you provided I finally received the expected response! 

I had been trying different transiever modes along with variations of the command syntax you had suggested earlier but I hadn't found the correct combination until now.   Now I can set about trying to make this thing work for me.

Thanks, bolt! Your assistance has been invaluable and very much appreciated.:)

P

[Wayne.C]

Thanks for the status update.  Glad I could be of help.

[arbit]

I am using a Yokogawa UP-550 controller and am having similar issues. I have an older version of Labview(6.1) and am unable to see the vi that you have attached. Could you please attach a screenshot?
Thank you.