Location5 (offset register address)

Location5 is used to specify an offset (one relative) to a particular coil, input status, holding register, or input register. It is important to realize that Location5 is used to specify an offset, not an absolute address. For example, say that the value from holding register 40083 is to be read and that the first holding register begins at 40001. One would specify 83 in Location5, not 40083. The correct absolute address, 40083, will be accessed as long as one specifies a function code of 3 in Location3 (for example, Location3=103).

For Modicon Hardware: function codes 1 and 5 begin at coil 1, function code 2 begins at input 1001 or 10001 or 100001, function codes 3 and 6 begin at holding register 4001 or 40001 or 400001, and function code 4 begins at input register 3001 or 30001 or 300001. For Honeywell Hardware: I/O locations range from 0 to 4095 and registers locations start at 4096.