PC to VL130 485

[idssteve]

We’re tasked with configuring a PC running SD Card Suite to access SD card data out of four VL130-33-TR20's via 485.  But that’s an issue for later discussion.  Before getting that far we’re wanting to establish PC connection to each individual VL130s.  The only successful PC connection we've accomplished is after setting the Com1 jumpers to 232.  Everything seems to communicate well through the VL130's Com1 from the PC's 9 pin serial port in that mode.  This PC is a Panasonic CF-30 with built in 9 pin serial port. 

 

Setting Com1 jumpers back to 485 the PC is unable to connect to any of the four VL130s.  Either via 9 pin serial or by 485.  Everything is 9600, 8N1.  We’ve tried a serial 232 to 422 converter (BB elect 422LP9TB), a usb 485 converter (AD USB-485M) and a uLinks USOTL4.  All old standbys that have served well on many projects, FWIW.  We’re preparing to order a Unitronics MJ10-22-CS35 and a M90-19-R4.  Unless you have other recommendations?

 

Till those devices arrive, I’d like to see if you guys can recommend anything to check? 

 

Thanks. 

 

[lawry]

Why not try ethernet

[Alexander]

What type of cable are you using when you are connecting to the V130's? If you navigate through Info-Mode within the controller how is the COM port set up in the software, is it for RS232/RS485? Is there an option to switch the software configuration on the controller?

[idssteve]

Thanks for the replies.  Ethernet's on the list of possibiltiies.  Right now i'm just trying to get a single individual V130 to com with a laptop on RS485.  Cable is about 60" long, 26AWG, 6 conductor, Copartner #E119932-U with molded on 6pin rj12. . 

 

Info Mode into "Communication", 1. Serial, 1. Com1, shows: 

 

Com1 - RS485

 

Prtcl:  Modbus,  ign Brk: N

Settings:  9600  ,8,n,1,N 

Tx/Rx:  00000   00000

Silence:  2.50ms

 

Also ...

 

Menu:

5. Setup

Modbus RS485 ID:  106

[Alexander]

Are you connecting straight from the PC to the PLC? If this is the case, or if the PLC is on the end of an RS485 communications network, you will need to have RS485 termination set on the PLC. It is possible that the controller is not set for communication which could be why you are unable to connect to the unit.

 

When trying to connect from VisiLogic is the baud rate also set for 9600?

[idssteve]

Yes,  We're connecting straight from the PC to the PLC.  Network to the four PLCs to come later but just want to see direct connection as first step.  The PLC's Com1 485 termination jumpers are "on".  We've tried "off",

also.  VisiLogic settings are:

 

Connection Type:  Serial

Baud Rate:  9600

[idssteve]

Sorry about loosing the last post before finishing. 

 

VisiLogic settings are:

 

Select Conntion Type:  Serial

PC Port:  Com 8

Baud Rate:  9600

TimeOut:  4 sec  (we've tried everything up to 30 sec)

Retries:  3

 

Communicate with OPLC:  Direct Connection

We've also tried Within Network (Unit ID)  106

[Alexander]

Do you know the pinout for the serial adapter that you are using? Our serial cables come standard with an adapter, MJ10-22-CS25, that is designed to work with our devices.

 

For RS485 you should only need to use pin 1 and pin 6 which are the A Signal (+) and B Signal (-) respectively. Pins 2-5 are used for RS232 only.

[idssteve]

We're in process to order your adapter and cable but the adapter we're currently trying is a ULinx USOTL4.  It's one of those with B(+) and A(-) designations.  We've tried both ways but B(+) is tied to RJ12 pin 1.  A(-) is tied to RJ12 pin 6.  A DVOM confirms idle voltage of +4V on B(+) relative to A(-).  Should we need to address bias in this short cable?  Also, we're unclear as to where to tie SG.  SG is currently tied to RJ12 pins 2 & 5 but we've tried floating it and also tried tying it to PLC's Terminal 3 chassis ground.

[Alexander]

When connecting RS485 devices within a network the terminals should not cross. Positive should connect to positive and negative to negative. Different devices may designate A or B differently, but you will need to connect the positive to our A signal (+) and negative to our B signal (-). Modifications may have to be made to the cable based upon it's designated pinout. You can reference the RS232/RS485 pinout within our controllers installation guide.

 

There should only be a potential issue with the voltage if it exceeds +/- 10V.

 

The SG is not going to connect to any of the RJ11 pins, but it is recommended to be grounded to earth.

[idssteve]

We've only crossed the terminals long enough to try.  They are + to 1 and - to 6.  We've also tried a different usb to 485 adapter with the other A(+), B(-) designation.  Also tried a 9pin to RS422-485 adapter plugged into the laptop's serial port #1.  No joy. 

 

No voltages exceed 5v so no bias needed?  We've returned the SG to the PLC's terminal #3 which is also bonded to earth ground.

 

Can you recomend a vendor that might overnight us a MJ10-22-CS25 and a M90-19-R4?  We're having difficulty finding one. 

 

Thanks for your efforts.

[Alexander]

For availability and shipping you would need to consult our sales department. You can find their contact information on our website using the following link:

 

http://www.unitronics.com/contact-us/contact-us-form

[idssteve]

We will get Unitronics adapter and update.  Thanks. 

[Joe Tauser]

From an earlier post Info Mode shows the protocol as "Modbus" - the PLC program may be grabbing your port.  Try loading a blank program and see if your luck changes. 

 

Post your code and I'll load it into something here and try my converter (I use a Novus Automation USB-i485)-

http://www.novusautomation.com/downloads/Arquivos/flier%20usb-i485%20converter.pdf

 

 

Shameless self-promotion: we stock them - $195.00.  I am in St. Louis, MO.

 

Joe T.

[idssteve]

Thanks Joe. I'll PM you.

[Joe Tauser]

I have talked with Steve over the phone and got a lot more detail on his application.  The short version is he is working on an OEM piece of machinery and has no access to the original program.

 

The machine was designed to communicate with a SCADA system over RS485 Modbus.  The machine is datalogging to the SD card, and the end user wants to extract data via SDTools to his computer so he doesn't have to open the machine and take the SD card out to download the data.

 

Here's where it gets weird.

 

SDTools, like all Unitronics software, uses PCOM as it's protocol.  PCOM is not working over RS485.  At all.  I set up a PLC on my table, set the dip switches to RS485, opened Visilogic, and tapped the "Get OPLC information" button.  Nothing but a communication error.

 

I set the PLC up as a Modbus slave and did the same with a Modbus simulator.  Everything works perfectly with Modbus on RS485.

 

I am sending a more detailed report to Unitronics support.  I will update this post when I have more information.

 

Joe T. 

[idssteve]

Now knowing that PCOM isn't working on 485, we've set up the four PLC's on modbus and the customer is now data logging via SCADA. Extracting the actual log from the SD card is still the long term goal but modbus is working ok, for now.

Thanks!

[Alexander]

When configuring the COM port to MODBUS the break signal switches the com port to RS232 PCOM and then you are unable to communicate with the PLC.

 

We found a workaround for this issue:

 

There is a system bit that turns on when break signal occurs SB 330,331, and 332 for COM port 1, 2, and 3 respectively. You can use this system bit to change the com port setting to RS485 again (since the break signal changes it to RS232 by default).

 

As you can see in the attached application after the SB 331 for COM 2 rises, we wait 5 seconds and change the com port settings to RS485. The disadvantage of this workaround is that you will need to try establishing the communication 2 times, the first time will change the com port to RS485 but you will receive error message that there is no communication but in the second time you will be able already to communicate. We tested it here using direct connection and also by network ID and it works properly.

 

For customers that wish to re-establish communications afterwards with the original protocol SB 133 and 136, data transmit and receive can be used to power a timer when not active. After a pre-determined length of time this can re-initialize Modbus communications.

 

Attached below is the required logic, as well as the program.

 

 

http://forum.unitronics.com/files/file/39-%7B%3F%7D/