signed long...modbus plus

We are reading a signed long via modbus plus into a quantum PLC using fast trac software. We receive the data in two consecutive registers. Now we need to concatenate the 2 16 bit registers into one and use that data throughout the program. What would be the best way to achieve this?

If you are using FasTrac software then your program is actually written in 984 Ladder Logic.

Why do you want them in one register?
The maximum value a 16 bit register can only handle is 65535. 984LL does not support 32 bit registers. 984LL double precision math instructions use two consecutive registers in order to handle values up to 99,999,999.

Do you want to take two seperate 16 bit integers and "create" a double precison word using two consecutive registers?