Simultaneous RFID Reader - PN: 1568-24738-ND

Sensors NFC & RFID
1

Hi Looking for some help. I been testing the RFID reader hooked up to a raspberry pi but not getting and scan reads. Below is a summary of what i have tried so far

Setup Summary

Device: SparkFun Simultaneous RFID Reader - M7E (WRL-24738)
Connection Method: USB-C to Raspberry Pi 4 and macOS
Switch Position: Tested in both “SER” (Serial) and “USB” modes
Operating Systems: Raspberry Pi OS (Linux) and macOS
Serial Devices Detected:

  • /dev/ttyUSB0 on Pi
  • /dev/tty.usbserial-10 on Mac

What’s Been Tried

1. Power & Connectivity

  • Reader powered via USB-C (red power LED confirmed on)
  • USB cable verified to be data + power capable
  • Switch toggled and tested in both USB and Serial modes
  • Serial device successfully detected on both Raspberry Pi and Mac
  • Baud rate set to 115200 (as specified in docs)

2. Terminal + Python Testing

Terminal Test:

bash

CopyEdit

screen /dev/ttyUSB0 115200
  • Screen opens and closes cleanly
  • No feedback or response when tag scanned (even <5 cm)

Python Script:

python

CopyEdit

import serial
import time

SERIAL_PORT = '/dev/ttyUSB0'
BAUD_RATE = 115200

try:
    with serial.Serial(SERIAL_PORT, BAUD_RATE, timeout=1) as ser:
        print(f"Connected to {SERIAL_PORT} at {BAUD_RATE} baud.")
        inventory_command = bytearray([0x04, 0x14, 0x01, 0x00, 0x15])  # Inventory command
        ser.write(inventory_command)
        print("Sent inventory command. Waiting for response...")
        time.sleep(1)
        response = ser.read(64)
        print("Response:", response)
except serial.SerialException as e:
    print("Serial error:", e)
  • Python successfully connects to device
  • Command sent but no response
  • No tag data, no blinking read LED

Confirmed

  • Device powers on
  • USB cable supports data and power
  • Serial port recognized on both Mac and Pi
  • Switch positions tested (USB + SER)
  • Tags placed within 1–5 cm of onboard antenna
  • No tag reads occurred
  • Python environment with pyserial installed and working
2

Looking at the Python code, the inventory_command/ data you send is NOT valid nor understood by the M7E. On the Raspberry pi install the MercuryAPI. Also see other posts like M7E Hecto Best way to update Online Database

3

Ok so Ive been able to connect it and get some reads happening using the mercuryapi docs and libraries.

The issue i’m now having is I can get the reader to run a continuousread but then when it stops it needs to be power cycled to get the reader to work again. Is this a known issue and if so how can I get it reset and start reading scans again without power cycling?

4

make sure to add strong enough power supply., The M7E / M6E are very sensitive to that and show the kind of bebaviour you decribe. The Raspberry is not providing enough. There are many articles in this forum about that. As you add a good power supply, also add a cooling block for the M7E. With higher read / write powers it because hot quickly. When too hot, > 72 celcius, it stops and you have to wait untill ik cools down.