4-channel Isolated Digital Input and 4-channel Source-type Isolated Digital Output Module.The tM-P4A4 provides 4 channels for digital input and 4 channels for digital output, each of which features photocouple isolation. The tM-P4A4 supports source-type output with short circuit protection, while input is sink-type. All input channels can be used an 16-bit counters. There are options for configuring power-on and safe digital output values. 4 kV E..