HART is a serial transmission procedure with which additional parameter data such as measuring ranges, attenuation etc. can be sent to transmitters and actuators over a 4 to 20-mA current loop. The HART jobs for each channel can be remotely initiated over the PROFIBUS DP. This usually takes place from the central engineering system of the SIMATIC PCS 7 process control system per SIMATIC PDM.

The modules with HART have the following features:

• Connections compatible with the conventional analog modules of the ET 200M
• Additional communications possibility over the current loop
• Up to 8 analog channels per module (2 analog channels with Ex modules; 6 analog channels with safety-related SM 336 F‑AI HART module)
• Each channel is a primary master of the HART protocol
• Selectable input range per channel (AI):
  • 0 to 20 mA (without HART function)
  • ± 20 mA (without HART function, not with Ex module or SM 336 F-AI HART module)
  • 4 to 20 mA (with/without HART function)
• Selectable output range per channel (AO):
  • 0 to 20 mA (with/without HART function; in the case of Ex module, only without HART function)
  • 4 to 20 mA (with/without HART function)

Additional functions of the 6ES7331-7TF01-0AB0 and 6ES7332-8TF01-0AB0 HART analog modules:

• Supplementary HART variables (up to 4 per channel, up to 8 per module) allow the transmission of additional values from/to the HART devices
• Modules can be used redundant (channel-granular redundancy)

Additional functions of the SM 336 F‑AI HART module:

• Modules can be used redundant (channel-granular redundancy)
• HART communication can be activated safety-related in online mode, or switched off

Parameterization

• For the analog input modules (AI), it is possible to parameterize e.g. conversion time, input range, limits, alarms, smoothing of measured values
• For the analog output modules (AO), it is possible to parameterize e.g. output range, response on stoppage of AS (CPU), diagnostics
• Remote parameterization (per PROFIBUS DP) of the HART transmitters and actuators with SIMATIC PDM
• It is still possible to parameterize the HART devices using an operator terminal (handheld).