Disadvantages
There are disadvantages to using fieldbus compared to the 4-20 mA analog signal standard (or to 4-20 mA with HART):
- Fieldbus systems are more complex, so users need to be more extensively trained or more highly qualified
- The price of fieldbus components is higher
- Fieldbus test devices are more complex compared to a (high-spec) multimeter that can be used to read and simulate analog 4-20 mA signals
- Slightly longer reaction times with fieldbus, depending on the system
- Device manufacturers have to offer different versions of their devices (e.g. sensors, actuators) due to the number of different (incompatible) fieldbus standards. This can add to the cost of the devices and to the difficulty of device selection and availability.
- One or more fieldbus standards may predominate in future and others may become obsolete. This increases the investment risk when implementing fieldbus.
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