IEC 60870-5-104 and Modbus gateway guides

Practical guides for engineers who connect Modbus devices to IEC 104 and IEC 101 SCADA systems

Modbus to IEC 104 mapping guide

Choose IEC type IDs for coils and registers, plan IOAs and common addresses, scale values and map commands.

IEC 104 type IDs and cause of transmission

ASDU structure, the common type IDs, every important COT code, quality bits and typical message sequences.

IEC 104 vs IEC 101

Serial FT1.2 vs TCP/IP, balanced and unbalanced mode, field sizes, time tags and when to use each.

IEC 104 t0-t3, k and w troubleshooting

What each timer and window parameter does, safe defaults and a symptom-by-symptom troubleshooting table.

Modbus float byte order for IEC 104

ABCD, CDAB, BADC and DCBA explained with a worked example, and how to send the value as M_ME_NC_1.

Max IEC Gateway user manual

How to install and configure the gateway, step by step with screenshots: user manual.

Modbus guides

For the Modbus side (register addressing, function codes, RS-485 wiring, timeouts and exception codes) see the guides on the ModbusBB site.