Issue
What is the significance of the 'H' suffix on an M340 or M580 part number?
Product Line
Modicon M340, Modicon M580
Resolution
An industrial installation environment can be significantly degraded by condensation and pollution:
• High values of relative humidity & temperature simultaneously.
• Presence of air contaminants such as salt mist or corrosive gases.
• Dust and other solid contamination
The 'H' indicates a 'Hardened' product that will run at extended heat and humidity ranges along with offering protection against contaminants.
See attached document.