Isotech produces two eight way selector switches, one for resistance thermometers Model 954 and Model 958 for thermocouples. These switches have been designed for use in conjunction with our TTI range. The switches allow easy selection of connected sensors. They can be operated from either the front panel switch or from an RS232 interface that is provided as standard. Channel status is indicated via front panel LEDs. The Selector switches can be located adjacent to the sensors being calibrated, giving more flexibility than a permanently connected or stacked system. The PRT Switch has 4mm terminal posts that can accept bare wires or 4mm plugs. The thermocouple switch has eight miniature thermocouple connectors. These thermocouple connectors are thermally bonded to a platinum resistance thermometer that measures the temperature of the connector and hence the “cold junction”. The TTI range temperature indicators feature the ability to measure a remote cold junction and this permits a mixture of thermocouple types to be connected through the box. The I-Cal software supports Switchbox models 954 and 958 and, for automatic operation, two boxes can be connected together with a “master / slave” lead allowing them to be controlled from a single RS232 port and up to 16 sensors to be switched. The software can automatically switch between the boxes and connect the appropriate output to the TTI. This 16 channel operation is not convenient without the software and manual operation of two boxes together is not recommended.