Reading 3X registers is usually done in a block.

Sample Coding
Slave Address = 1
Reading 6, 3X Registers – code 4
V1 = 239.9V, V2 = 239.7V, V3 = 239.7V
I1 = 499.8A, I2 = 499.3A, I3 = 499.3A
Start Address = 6, number of WORD registers required = 12 (0C hex)
Number of values returned = 6, 32 bit floating point (24 bytes)

Message Packet To SLAVE
01 04 00 06 00 0C 10 0E

Response Packet From SLAVE
01 04 18 43 6F E2 28 43 6F A9 C8 43 6F A9 C8 43 F9 E0 E9 43 F9 A6 31 43 F9 A6 31 EC 6D