serial break

Hi,

I´m developing an application for which I want to operate a NDP and a Vector over an ethernet connection by using serial to ethernet converters.
The problem is that I´m not able to transmit a hard break through these converters. For the vector, I think, this is not a problem because it supports soft breaks (is this correct?).

But what can I do about the NDP? Is there any other way to generate a break? The only solution I have on my mind is to switch it on and off (I do have digital IO lines availbale, which I could use to switch the power supply).
Do you have any other ideas?

thanks!
Andreas

Hi Andreas,

As you point out, this is not a problem for the Vector since it supports soft break. In fact, this type of problem is the reason why we developed the soft break. " />'>

The NDP represents a challenge though. Cycling power is not the same as a hard break so you should not try that. But it is a good idea to use one of the digital IO lines to produce the break.

I suggest that you use an IO line to force a high level on the RS232 line going into the NDP. You need to add a bit of circuitry though. The most straight forward way to do this is probably by connecting an RS232 transmitter to the same line as the one coming from your Ethernet to serial device. Use the digital IO line to enable/disable the transmitter and hard wire the input of the transceiver to a high level. You should probably add a resistor, in series between the Ethernet to serial device and the added transmitter, for protection and to make sure that you are able to drive the line high with your added circuitry.

Depending on the number of extra IO lines you have, you may be able to supply power to the new transceiver by parallelling IO lines that are set to a high level.

Best regards,

Sven Nylund

Hi Sven,

thanks for your answer. I thought it would ne easier.
I thought the NDP was in command mode whenever the power is switched on. But it isn´t, it starts measuring. Is there any switch, which enables/disables this auto-recording feature?

If not - you are right - in this case it doesn´t help to cycle power.

Can you give me a few more details about the circuit you proposed? What kind (or what brand) of serial transmitter do you recommend, and what kind of resistor should I use?
The power supply is not a problem, I do have 5 V and 12 V power available.

best regards,
Andreas

Hi Andreas,

Here is a cuircuit example that you can try. There is a large number of transceivers available if you prefer another package.

I suggest that you measure the voltage level and timing with an oscilloscope to make sure that you can use the suggested resistor value.

Best regards,
Sven