How can I use a PIC to read data from one of these devices and store them?
Il titolo non è molto chiaro... infatti non so neanche di cosa sto parlando!
I think the easier way is to use a multimeter with RS232 port used to send data to a PC (datalog). Just connect a PIC with USART inside (or write a routine to manage this) and a level converter IC (MAX232). After this you only need to know the protocol used by the multimeter to decode the data coming from the meter.