Xtrem Protocol

Version: 3.007 Device: XTREM / XTREM-S Weighing Module Standard: OIML R76:2006 / EN45501:2015 compliant

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Overview

The XTREM communication protocol allows a terminal or host controller to exchange data and commands with the XTREM weighing module. The device transmits and receives ASCII-coded frames over a serial interface (RS232, RS485, Wi-Fi, or Ethernet, depending on configuration).

Since we are using the Ethernet interface we need to provide some kind of DHCP to assign an IP - Address to each XTREM Device. They then may be addressed via a broadcast IP (e.g.: 192.168.4.255/24). A Unicast communication is applied through the device ID inside the XTREM Frame.

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Frame Structure

Each message—both query and response—has the same format:

STX ID_O ID_D F D_ADDRESS D_L DATA LRC ETX

Field	Description	Length (bytes)
STX	Start of message (ASCII 02h)	1
ID_O	Sender address (2 ASCII hex chars)	2
ID_D	Destination address (2 ASCII hex chars)	2
F	Function code (R, W, E, etc.)	1
D_ADDRESS	Data address (register, 4 ASCII hex chars)	4
D_L	Data length (2 ASCII hex chars)	2
DATA	Optional data field	Variable
LRC	Longitudinal Redundancy Check (2 ASCII hex chars)	2
ETX	End of message (ASCII 03h)	1

In the default configuration the Frame also requires a CRLF at the end.

Example:

STX ‘1’ ‘7’ ‘0’ ‘1’ ‘R’ ‘0’ ‘1’ ‘0’ ‘1’ ‘0’ ‘0’ LRC ETX CR LF

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Function Codes

Function	ASCII	Hex	Description
R	R	52h	Read request
r	r	72h	Read response
W	W	57h	Write request
w	w	77h	Write response
E	E	45h	Execute command
e	e	65h	Execute response

Write response codes

• '0' – OK
• '1' – Write denied (sealed)
• '2' – Read-only register
• '3' – Invalid value / out of range

Execute response codes

• '0' – Executed successfully
• '1' – Blocked by seal switch

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LRC Calculation

The Longitudinal Redundancy Check is a one-byte XOR of all message bytes, excluding:

• STX
• ETX
• The LRC itself

Example C function:

unsigned char LRC(unsigned char* s) {
    unsigned char lrc = 0;
    while (*s) {
        lrc ^= *(s++);
    }
    return lrc;
}

Example Rust function:

pub fn compute_lrc(data: &[u8]) -> u8 {
    data.iter().fold(0u8, |acc, &b| acc ^ b)
}

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Key Data Registers

Address (hex)	Description	Type	Notes
0000h	Serial number	R	Factory-set
0001h	Device ID	RW	Network address
0007h	Hardware version	R	Read-only
0008h	Software version	R	Read-only
0009h	Sealing switch status	R	0=UNLOCK, 1=LOCK
0010h	Baud rate	RW	0–4 → 9600–115200 baud
0013h	Stream mode output rate	RW	Time in ms
0100h	Device state	R	Status bits (power, Wi-Fi, ADC, etc.)
0101h	Weight value	R	Gross weight
0102h	Tare value	RE	Read/Execute
0103h	Net weight	R	Gross − Tare
0110h	ADC counts (instant)	R	Raw ADC data
0111h	ADC counts (filtered)	R	Post-filter data
1010h	Stop stream mode	E	Execute
1011h	Start stream mode (weight)	E	Continuous output
9999h	Device reset	E	Software reset
EEEEh	Factory reset	E	Restores defaults

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Post-Factory Reset Configuration

After performing a factory reset, several registers must be configured to ensure proper operation of the device.

Note: The unit may remain set to 'g' after a factory reset, but the values received may be in 'kg' depending on the device configuration.

The following registers should be reviewed and set as required:

1. Address: 0022 | Max (Max1) (scale maximum capacity) The default value for this register may vary between devices (e.g., 60000 or 6000). Set this value to 6000 to ensure correct operation.
2. Address: 0023 | e (e1) (scale interval)
3. Address: 0026 | Decimal position