Why would the NI software hang-up with greater than 16 devices on the fieldbus after the configuration is downloaded?

[hhsatBeck]

I am using a PCMCIA card with a single port in a laptop with the 3.2 NI-FBUS SW. I have 27 devices on the Fieldbus and the Configurator detects all of the devices. In the Function Block Application, an output of an Input Block (4-20mA fieldbus transmitter) is connected to the Cascade inputs of Analog Output Block for 26 fieldbus devices. The configuration is saved then downloaded.  When the download is complete, the NI software appears to hang up. Monitoring the fieldbus with an oscilloscope shows that the fieldbus communications goes dead and the power supply level is +24V. If I reduce the number of fieldbus devices to 16, perform the configuration and download, the NI software works fine and does not hang up; the communication signal monitored on the fieldbus is still active.  Why would the NI software hang-up with greater than 16 devices on the fieldbus after the configuration is downloaded?

[Vince Shen]

Hello,

I would like to get the following information about this issue.

1. It is ok when you use 16 devices. Does this mean that 16 is the maximum number? Even 17 devices can not work properly?

2. Beside PCMICA-FBUS card, is there any master device in network?

3. What the type of power hub you are using? Is the power hub purchased with NI-FBUS interface card?

4. During the download process, is there any error message shown in the Configurator's status/download/error window?

Also, could you please send us the screenshots if you think it is necessary?

You can sent to our support email, fieldbus.support@ni.com

Thanks!

[hhsatBeck]

Hello VInce,

Response to your questions.

1. I did not give you a proper count. Here is the fieldbus configuration:  16 fieldbus compatible circuit boards, a fieldbus power supply, a fieldbus transmitter, and the NI PCM_CIA FBUS card as the master device. If I increase the fieldbus compatible circuit boards to 17, the fieldbus signal drops out at the end of the configuration download when the window asking if the configuration should be saved is displayed.

2.  The PCM-CIA FBUS card is the master device.

3.  The power hub is  ABB PC900-NR with the bus termination ON.

4. There are no error messages during the download process.

This fieldbus system experiencing this problem is an in-house product test system. The system is used for a circuit board burn-in test. Our circuit boards with the fieldbus interface is connected into a backplane capable of interfacing 27 circuit boards to the fieldbus network.  The system consists of the PCM-CIA FBUS card in a Dell laptop PC, an ABB PC900-NR bus power supply, and a PR Electronics 6350 Fieldbus Transmitter all external to the burn-in oven. The interface backplane for the circuit boards under test is in the oven. The cabling distance is approximately 10-15 feet and proper bus termination is implemented.  

The initialization, configuration, and configuration download to the circuit boards are performed at room temperature.

Thanks for any help you can provide.

hhsatBeck

[Vince Shen]

Hello hhsatBeck,

Thanks for your detail information. I have forworded this issue to our R&D department. I will let you know the conclusion as soon as possible.

Sorry for the inconvenience.

[Vince Shen]

Hi hhsatBeck,

One more information I would like to confirm.

PCMICA-FBUS card is the master device, how about the other devices. Are there any other devices also set to master except PCMICA-FBUS card?

[hhsatBeck]

Hi Vince,

No other devices are set to master; the PCM_CIA card is the only master.

hhsatBeck