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Brief No Contact from 2x MD5 to MC43 on Equipment Start
We have a multi-master setup with MC43 headmaster, MC41, and 2 MD5 displays. On initial power up all modules are communicating normally without error. For a brief moment on engine start both MD5s report no contact to the MC43 and values from the CAN bus stop updating on both displays. First assumption was a voltage drop issue on the MC43 but we scoped power to ground at the MC43 during startup and we are well above the 9V minimum. We also ran a CAN trace on the bus to check for CAN errors but saw no issues there either (no CAN errors reported by anything on the IQAN side either other than the no contact error).
The no contact is transient, it appears to clear up almost immediately. There is no indication of no contact on either the MC43 or MC41 LEDs during this period. LEDs are displaying the normal running pattern. When the displays are frozen all of the control functions still work, but the display does not update to reflect our inputs.
The displays will resume updating values only if we transition to another user-created MD5 page and back. Until we go to another screen it will never resume updating values on the display. So far we have replicated on IQANdesign versions 7.05.19 and 7.05.27. Other than this specific issue everything is operating without problems.
Does anybody have any suggestions on potential causes or tests to narrow down the issue?
Customer support service by UserEcho
I assume you are using the Diagnostics bus? In the CAN trace, do you see that the max time between Proprietary A messages go up slightly when you have the problem?
The symptom where the values on the display page do not resume updating after the glitch may be a bug, I have seen this before in systems with MD4 and MC4, when there is a very short glitch.
Thanks for the response Gustav, we ended up figuring it out. I had assumed that the problem was at the MC43 due to the error message but it seems like it was at the MD5s. They appear to be a bit more sensitive to changes in system voltage. We tested a dedicated power supply with the MD5s and the issue went away.
Oddly we never saw any other symptoms with the MD5 that would be related to undervoltage, just this brief CAN dropout and subsequent freezing of values.