"""
Example: Modbus
This example shows how to connect to remote IO modules through modbusTCP.
This example works with all SLM Series:
- Discrete input modules such as SLM-SIM-8.
- Analog input modules such as SLM-AI-8V.
- Input/Output combo modules usch as SLM-ACDCI-8NP-RLY8
- Relay Coil modules such as SLM-RLY-16
- Analog output modules such as SLM-AO-8-V
- Thermocouple input modules such as SLM-THM-4
Modules used:
Slot 01: SLM-ACDCI-8NP-RLY8
Slot 02: SLM-AI-8V
Slot 03: SLM-AO-8-V
Slot 04: SLM-THM-4
_____ _____ _____ _____ _____
| S || S || S || S || S |
| L || L || L || L || L |
| M || O || O || O || O |
| - || T || T || T || T |
| M || || || || |
| X || 0 || 0 || 0 || 0 |
| || 1 || 2 || 3 || 4 |
| || || || || |
¯¯¯¯¯ ¯¯¯¯¯ ¯¯¯¯¯ ¯¯¯¯¯ ¯¯¯¯¯
Written by Synergy Logic
Copyright (c) 2025 Synergy Logic, LLC
Licensed under the MIT license.
"""
from pymodbus.client import ModbusTcpClient
import time
# Ip address of SLM-MX
client_ip = "192.168.1.105"
unit_id = 255
# Open modbus connection
client = ModbusTcpClient(client_ip)
client.connect()
# IMPORTANT!!! Refer to SLM-MX Configuratior for the modbus IO register map.
while True:
# Read 8 discrete inputs starting at address 0
result = client.read_discrete_inputs(0, count=8)
print("\nDiscrete Inputs 1-8:")
for index, value in enumerate(
result.bits ): # Use .bits for discrete input parsed data
print(f"Input# {index + 1}: {value}")
# Write the results from the discrete inputs to the 8 coils starting at address 0
client.write_coils(0, values=result.bits)
# Read the coil status of all 8 coils to verify successful write.
client.read_coils(0, count = 8)
print("\nCoil Statuses 1-8:")
for index, value in enumerate(
result.bits ): # Use .bits for reading coil status parsed data
print(f"Input# {index + 1}: {value}")
# Read 8 analog inputs starting at address 0
result = client.read_input_registers(0, count=8)
print("\nAnalog Inputs 1-8:")
for index, value in enumerate(
result.registers): # Use .registers for reading analog count parsed data
volts = round(value/8192 * 10, 3) # Convert counts to volts. value in engineering units = counts / 2^(bit resolution) * max value
print(f"Holding Register#{index +1 }: {value} counts, {volts}V")
# Write Analog output channel 1 at address 0
counts = int(3.3 / 10.0 * 4096) # Convert volts to counts. counts = value in engineering units / max value * 2^(bit resolution)
client.write_register(0, counts)
# Read 4 thermocouple input channels starting at address 9
result = client.read_input_registers(9, count = 4)
print("\nThermocouple Inputs 1-4:")
for index, value in enumerate(
result.registers): # Use .registers for reading analog count parsed data
print(f"Thermocouple channel#{index +1 }: {value} C")
#loop delay
time.sleep(1)
