... stable, reliable low power, supports 1 ~ 4 channels the digital TTL signal/contact closure signal, 1 ~ 4 channel analog (voltage/ ... of power polarity reverse connect.Performance index: Contact closure signal/TTL digital signal interface: Ø Independent 1 ~ 4 channel input, 1~ ... short circuit or openØ Output modes: the optional for 5V TTL / 24V TTL output, or relay outputØ Relay output form: FORM C ...