Kuka KRC2 Devicenet with 16I/16O Phoenix contact - configuration error

    Quote from hydra

    what is it that you don't understand?

    No need to connect 120 ohms on both sides.

    Completely untrue. 120 ohm resistors are required on both ends of the trunk -- this is part of the DeviceNet bus specification. Any DN trunk that does not measure 60ohms (+/- 3-5) between CAN+ and CAN- (when unplugged from all devices) fails all standard DN tests.

    I have seen some, very short, DN cables operate, badly, at low baud rates, with only one termination resistor on one end, or triple resistors, but getting the terminations wrong causes DN to fail better than 95% of the time, in my experience.

    The only circumstances under which it is not necessary to add termination resistors is when one end of the trunk ends on a device that includes an internal termination resistor, and even then, that resistor must be activated (usually with a DIP switch). On a KRC1 or KRC2's MFC-card DN port, there is no internal termination resistor, and so adding one at the card is always required, unless that port is wired in the middle of a larger DN trunk (which still requires 120ohm termination on both ends).

    Quote from SkyeFire

    Completely untrue. 120 ohm resistors are required on both ends of the trunk -- this is part of the DeviceNet bus specification. Any DN trunk that does not measure 60ohms (+/- 3-5) between CAN+ and CAN- (when unplugged from all devices) fails all standard DN tests.

    I have seen some, very short, DN cables operate, badly, at low baud rates, with only one termination resistor on one end, or triple resistors, but getting the terminations wrong causes DN to fail better than 95% of the time, in my experience.

    The only circumstances under which it is not necessary to add termination resistors is when one end of the trunk ends on a device that includes an internal termination resistor, and even then, that resistor must be activated (usually with a DIP switch). On a KRC1 or KRC2's MFC-card DN port, there is no internal termination resistor, and so adding one at the card is always required, unless that port is wired in the middle of a larger DN trunk (which still requires 120ohm termination on both ends).

    I communicated when a single-sided resistor was installed in short connections. I haven't had a problem so far.

    Think before you talk, Read it before you think about it.

    Fran Lebowitz.

    Quote from hydra

    I communicated when a single-sided resistor was installed in short connections. I haven't had a problem so far.

    I once got an RS232 connection to work without a ground wire. That doesn't make it good advice to tell people to try wiring an RS232 connection with only two wires instead of three.

    As I said, it can work, sometimes, for very short runs, if you're lucky. Luck is not something to rely on.

    Quote from hydra

    I communicated when a single-sided resistor was installed in short connections. I haven't had a problem so far.

    This could work, BUT

    - where did you place your resistor?

    - what kind (brand) of module did you have on the other side?

    There exists modules

    - with integrated resistors which have to be activated by DIP Switch

    - with integrated resistors which are put in place automatically (if needed)

    If you tell us a story please tell the whole story and not just part of it

    As everyone (besides you) is telling, that two resisters are needed: believe them - this is true!

    You could argue

    - whether a 120 Ohms or 121 Ohms resistor should (must) be used

    - whether a carbon film or metal film resister should be used

    BUT you need two of them

    What do you mean by "so far"?

    Did you you run the system for minutes, hours, days?

    Over a year 24/7?

    What do you mean by "short connection"?

    A last advice:

    alway think about the "worst case scenario" never about "best case senario"

    Do you work in a lab or in the "real world"?

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