M580 generic modbus TCP DTM and re-transmissions

[dnordenberg1]

Hi!

Can someone explain exactly how the generic modbus DTM handles timeouts och re-transmissions?

As far as I can see there are three settings involved here, health timeout, repetitive rate and gateway/bridge device.

First I figure that health timeout works stand-alone, it is the time from when the first query is made until health bit toggles and the "last value" action is activated (hold or set to zero), right?

That part isn't to hard to understand but now, how and when is re-transmissions made? The documentation I can find does not mention this, only documentation which slightly hints about how it works is under the gateway/bridge device setting:

"Select the check box to enable this feature. The communication module doubles the timeout setting by increasing the number of re-transmissions to 6 (instead of the typical setting of 3)"

So when are these 3 (or 6) re-transmissions made? How does this setting doubles timeout as text say? Is re-transmissions made at a certain period like 1/3 (or 1/6 using gateway setting) of the repetitive rate time or is it depending on the health timeout time? It sounds like checking this setting would actually give the device half the time to respond then if it doubles the re-transmissions in a certain period of time?