Features 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.