Feature request: Optionally ignore modbus packet size restrictions, use TCP packet length

Bug #341708 reported by n1ywb
4
Affects Status Importance Assigned to Milestone
libmodbus
Invalid
Medium
Unassigned

Bug Description

For our in-house Modbus TCP implementations we ignore the silly 260 byte / 125 register limitation on modbus packet sizes. The "quantity of registers" field is two bytes and so can theoretically support up top 2^16 registers, and we allow that. For response packets we ignore the modbus packet length field and instead look at the TCP segment length to determine packet size.

n1ywb (jeff-laughlin)
Changed in libmodbus:
status: New → Invalid
Revision history for this message
Stéphane Raimbault (sra) wrote :

We can add a new method modbus_something (to not break the API) to remove this limit in mb_param. It's important to be conform to the standard and I'm agree to be able to workaround when it's silly!

With a unit test... :)

Changed in libmodbus:
importance: Undecided → Medium
milestone: none → 2.0.3
status: Invalid → New
Changed in libmodbus:
milestone: 2.0.3 → 2.2.0
Changed in libmodbus:
status: New → Invalid
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