The S300A/B communication module is suitable for ASCO 300, 200 series automatic transfer switch products. With the S300A/B, users can remotely obtain ATS position status, power status, voltage, frequency, and fault alarm signals. The module is compatible with ASCO Group1 and Group5 controllers, uses Modbus RTU communication protocol, has programmable addresses, supports up to 32 devices, selectable baud rates, provides fault alarm dry contacts, and can be connected to a Chinese interface LCD display screen.
The S300A/B communication module adds Modbus RTU remote monitoring to ASCO automatic transfer switches (ATS) in the 300, 200, 4000 and 7000 series. It supports up to 32 devices on a two‑wire half‑duplex RS‑485 bus and can be mounted on a standard 33 mm DIN rail.
The manual covers module features, wiring and installation steps, address and baud‑rate configuration via DIP switches, the Modbus register map for both S300A and S300B variants, and a troubleshooting guide with common LED indicators and fault‑alarm handling. This manual is written in Chinese.
What's inside
Features
Installation
Wiring and Connections
Configuration and Address Setting
Modbus Register Map
Troubleshooting
Specifications
Compatible Controllers
ASCO Group 1 and Group 5
Communication Protocol
Modbus RTU
Interface
Two‑wire half‑duplex RS‑485
Maximum Device Count
32 addresses (0‑31)
Baud Rate Options
9600 bps or 19200 bps
System Voltage Selection
220 V or 380 V (no extra power supply)
Frequently asked questions
How do I set the baud rate for the S300A/B module?
Use DIP‑1: set it up for 19.2 kbaud or down for 9.6 kbaud.
How can I change the system voltage setting?
Adjust DIP‑3: up for 380 V, down for 220 V, then power‑cycle the module.
How many devices can be addressed on the RS‑485 bus?
The module supports up to 32 devices, with addresses ranging from 0 to 31.