About the 12M9-003-A4
A module in the MM300 series produced by GE Multilin, the 12M9-003-A4 is a CPU Module that provides a Modbus R485 port, a thermistor input, and more. It also includes a sensitive ground input suitable for a 50:0.025 CT. This module fits into slot B along with the optional communications board. The CPU module is part of the base unit and necessary for proper function of the MM300 relay; as a result, it comes with all models of the series and should be replaced in the event that the system detects hardware damage. The modular, scalable design of the relay ensures that upgrading and replacing modules is a breeze.
The CPU module is able to accept either a negative temperature coefficient (NTC) thermistor or a positive temperature coefficient (PTC) thermistor. They can be directly connected to the + and - terminals of the module. The MM300 is able to specify the hot and cold thermistor resistance, and can automatically determine the thermistor type as NTC or PTC as a result. Users should disable the “Thermistor Trip” and “Thermistor Alarm” settings in the event that they choose not to connect a thermistor.
The optional communications board provides Fieldbus and Ethernet ports to the relay. Fieldbus is a group of protocols that are used in industrial automation environments and have been standardized as IEC61158. Fieldbus protocols allow controller systems to be connected in different topologies like the branch, star, daisy chain, and ring. The Ethernet option allows non-direct access to the relay, such as from laptop computers running the EnerVista MM300 software program.
