This digital controller provides accuracy of 0.1% of displayed value and a sampling rate of 0.025 second.
The difference between the HA401/901 and theHA400/900 is autotuning algorithm.

• High speed sampling : 0.025 sec.
• Single loop / Dual loop / Cascade control
• Multi-memory area (Up to 16 sets)
• Bar-graph display
• Dual digital communication ports
• Modbus, Profibus, and DeviceNet support

Autotuning a process with fast response may produce PID autotune constants that would fluctuate the process excessively.
In the HA401/901, PID autotune constants are settable in 1/100 units for accurate control. The HA401/901 are suited for applications that reach the set point in five (5) minutes or more. If the process is less than five minutes to the set point, RKC recommends adjusting the AT differential gap to less than 10 seconds (default value in the HA401/901) prior to autotuning. If the process is less than 30 seconds to the set point, the HA400/900 is recommended.