Siemens 6ES7138-4DA04-0AA0 Counter Module For SIMATIC S7-300 PLC

Siemens 6ES7138-4DA04-0AA0 Counter Module is a one-channel, 24 V DC counter expansion for the ET 200S distributed I/O system, designed to be mounted in the ET 200S rack and used with SIMATIC controllers in the S7-300 family. It provides a single counter input capable of counting up to 100 kHz and occupies a 15 mm installation width, making it a compact option for high-speed pulse counting in automation lines. The module supports Count and Measure operating modes, including cycle duration measurement and high-resolution counting, and exposes a 32-bit counter value that the PLC can read with clock synchronization to ensure consistent timing across multiple I/O channels. In practical applications, it is used to count encoder or sensor pulses and to measure timing characteristics in industrial processes, enabling precise event-by-event tracking and timing analysis in systems such as packaging, material handling, and conveyor operations.