Connecting Optical DO Sensors

Optical DO sensors include built-in electronics that must be powered. One must consider the power source for these devices. Hamilton offers a variety of cable configurations for different applications and situations.

VisiFerm® RS485 with Direct Connection to the PCS

These applications use 24 VDC directly from the control system and feature bare wire leads. The VisiFerm® RS485 provides a Modbus digital signal back to the control system. All VisiFerm RS485 products use the VP Connector.

VisiFerm Arc with direct cable connection

VisiFerm® mA and VisiTrace® mA with Direct Connection to the PCS (Two-Wire Loop Powered)

The VisiFerm® mA and VisiTrace® mA products are unique in that they are loop-powered optical DO sensors. The 24 VDC bare-wire power leads also transmit the 4–20 mA analog signal back to the control system. These products also include the HART digital protocol. An M12 connector is standard.

Loop-powered optical DO sensor

VisiFerm® RS485 with Third-Leg Power Supply

Powered cables are commonly used with the VisiFerm® RS485 sensors in applications where no power is available from the bioreactor or transmitter. A separate “third-leg” power supply uses available wall power to provide power to the sensor. These cables have a variety of connector options for use in bioreactors, including BNC, M16 Binder, AMP, and Lemo connectors, as well as bare wire leads for direct connection. The VisiFerm® RS485 uses a VP connector to mate with the cable. The VisiFerm® RS485 sensor can be powered through the cable, and the ECS signal will mimic the nano-ampere signal typical of polarographic sensors.

Sensor and cable with “third-leg” power supply