Rs 422 interface dameged test

[t2dj]

Hi guys I'm currently working with a Binder Oven  and at the moment I believe the oven's Rs422 interface is dameged but I need to find a valid way to test it. 

To communicate to this oven I am using a Startech 1 port Rs232/422/485 Over IP Adapter. 

The interface to the oven is Rs422, although the protocol used to communicate is Modbus. 

Researching Rs422 I found that is a differential bus having 4 lines to communicate.

Rx+

Rx-

Tx+ 

Tx- 

Now when I measure the voltage levels on the Star tech device I find that the Tx+ and Rx+ lines are +5V and the TX-/Rx- lines are 200mV. 

When I try measure the interface on the Binder Oven I find that there is no voltage at all on these lines? (Measuring using an oscilliscope and multi meter) 

My question is is there a valid way to test an RS-422 interface that is on a machine and not on a PC's communications port? 

I have searched all over online but I still havent found a valid test.

Thank You.

T2DJ. 

[johnsold]

A quick Google search found this document from Texas Instruments which includes tests. I did not study the tests in detail but it appears that they could be used on your machine.

Lynn

[t2dj]

Hi Lynn, thank you for the reply.

I have looked at this document and it's not what I was looking for. 

I'm trying to test the actual port/ connector to see if it is functioning correctly.

Would you know of any other tests? 

Something like a loop back test or something? 

Thanks. 

T2DJ. 

[AudioVideoDisco]

HI T2DJ,

I cannot find any definitive tests for this online but you may be able to implement a type of Loop back test as you mentioned.

You could try monitoring the serial lines using some hardware and then sending some data through the interface. Try contacting Binder directly on this as they will be able to give you more information on the type of signals you should be able to send through the port and will certainly be able to provide some information on troubleshooting the oven.

Paul

[Dennis_Knutson]

Unless the oven has a mode where you can write and read to its port with its control panel, the idea of a loopback test is silly.

Why do you think the port is damaged? Was it once working and now its stopped? Are you able to communicate to a different oven with the exact same hardware and software? Trying to measure the voltages when the port is idle is a bit of a waste of time, as far as I am concerned.

[t2dj]

Hi Dennis_Knutson, communications have never been established, this is the first attempt.

The software was given to us by Binder themselves.

I believe its damaged as

 a) Their software does not function correctly (I cannot control the oven). 

 b) My research of the mod bus suggests that the transmission lines (even in idle state) are Tx+ = 5V Rx+ = 5V Tx- 200mV Rx- 200mV when I measure the mod bus attached to the oven I        have       found that there is 0V on all lines. 

 c) There is no turn on switch. 

 d) Within the Binder user manual it states that even when the user sends down a bad message (message with an error) the machine will respond with an error code (I do not get a response).

Hi Audio Video Disco, thanks for the reply, I'm currently talking to their service reps to find the problem. 

I will keep the post updated, but if any of ye guys (or any others) have any solutions they would be greatly appreciated. 

Thank You. 

T2DJ

[Dennis_Knutson]

The tx lines are differential and it does not sound like you are measuring correctly. The rx lines are differential inputs and I don't think you are measuring those correctly either.

Did you make the cable itself? Are you sure you have the RS422 adapter on your pc configured correctly?

I agree that you need to contact Binder but you have not convinced me that it must be a defective port. In any case, it is not an issue with NI hardware or software and this thread should probably be closed.

[johnsold]

I agree with Dennis that you may have other problems. It almost sounds as though your cable is not connected.  Verify the connections.

Lynn

[micrel96]

dear all,

I have exactly the same problem with a Binder thermal chamber (model MK53 E2).

Did Lynn scceded in solving the problem? was the interface defective?

thanks

Massimo

[t2dj]

It was... It turned out on this one that the controller was damaged. 

I contacted Binder, and they allowed me to borrow a new part to verify it, once I verified it we bought it.