# MODBUS Addressing High and Low Bytes **URL:** \ **Category:** Ignition\ **Tags:** ignition81\ **Created:** [October 18, 2021, 6:33pm UTC](https://forum.inductiveautomation.com/t/modbus-addressing-high-and-low-bytes/52070 "2021-10-18T18:33:45Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![pridesleap](https://avatars.discourse-cdn.com/v4/letter/p/f4b2a3/32.png) [@pridesleap](https://forum.inductiveautomation.com/u/pridesleap)\ **Post date:** [October 18, 2021, 6:33pm UTC](https://forum.inductiveautomation.com/t/modbus-addressing-high-and-low-bytes/52070/1 "2021-10-18T18:33:45Z")
Hello all. I have connected to a device using OPC MODBUS RTU over TCP. I’m receiving good data for most of the points I need to bring into the SCADA but I have a question about splitting up a 16bit packed register. I need to read the high and low bytes. I believe what I need to do is first bring in the full 16bit register as a tag and then use an expression tag to perform the read function with an expression. My questions are: 1. Is this a correct workflow? 2. If so, does anyone know what the correct expression would be? ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [October 18, 2021, 6:39pm UTC](https://forum.inductiveautomation.com/t/modbus-addressing-high-and-low-bytes/52070/2 "2021-10-18T18:39:25Z")
You’ve got the right idea. The expressions would look something this: High Byte: `({PathToRegisterTag} >> 8) & 0xFF` Low Byte: `{PathToRegisterTag} & 0xFF` ---
**Author:** ![pridesleap](https://avatars.discourse-cdn.com/v4/letter/p/f4b2a3/32.png) [@pridesleap](https://forum.inductiveautomation.com/u/pridesleap)\ **Post date:** [October 18, 2021, 6:52pm UTC](https://forum.inductiveautomation.com/t/modbus-addressing-high-and-low-bytes/52070/3 "2021-10-18T18:52:31Z")
Perfect! That worked a treat. Thanks for the quick resposne.