I propose we set up a temperature sensor network as described in attachment 1.

Here there are two types of units:

• BASE-GATEWAY
  • Holds the processor to talk to the network through Modbus TCP/IP protocol.
  • This unit itself has a temperature sensor in it. It is powered by a power adaptor or PoE from the switch.
  • Each base unit can have at max 2 extended temperature probes ENV-TEMP.
• ENV-TEMP
  • This is just a temperature probe with no other capabilities.
  • It is powered via PoE from the BASE-GATEWAY unit.

Proposal is

• to put 2 ENV-TEMP sensors (#1 and #2) along the Y-arm at the end and midway. These are powered and read through a BASE-GATEWAY (#A) at the vertex. The BASE-GATEWAY (#A) will serve as temperature sensor for the vertex.
• We put one ENV-TEMP(#3) at the X-end powered and read through by another BASE-GATEWAY (#B) at the midpoint of X-arm.
• Both BASE-GATEWAY are connected by ethernet cables to the network switch. That's it.

These sensors can be configured over network by going to their assigned IP addresses. I'm not sure at the moment how to configure the dB files to get them to write on slow EPICS channels.

We will have an unused port on the BASE-GATEWAY (#B) which can be used to run another temperature sensor, maybe at an important rack, PSL table or somewhere else.

In future, if more sensors are required, there are expansion (network switch like) options for BASE-GATEWAY or daisy-chain options for the probes.

Edit Fri Jun 18 16:28:13 2021 :

See this [wiki page](https://wiki-40m.ligo.caltech.edu/Physical_Environment_Monitoring/Thermometers) for updated plan and final quote.