Introduction
All Maple Systems HMIs programmed with EBPro (EasyBuilder Pro), including every cMT X Series and cMT Series model, are compatible with Hitachi EH-SIO. Configure your Controller and HMI/cMT with the following parameters to establish reliable communication.
HMI Settings
| Parameter | Recommended | Options |
|---|---|---|
| PLC type | Hitachi EH-SIO | |
| PLC I/F | RS232 | RS232, RS485 |
| Baud rate | 19200 | 9600, 19200, 38400 |
| Data bits | 7 | 7 |
| Parity | Even | Even |
| Stop bits | 1 | 1 |
| PLC sta. no. | 0 |
PLC Setting
| Parameter | Value |
|---|---|
| Communication mode | 19200, E, 7, 1 (default) |
Device Addresses
| Bit/Word | Device type | Format | Range | Description |
|---|---|---|---|---|
| B | X | HHHHh | 0 ~ fffff | External input-bit (X) |
| B | Y | HHHHh | 0 ~ fffff | External output-bit (Y) |
| B | M | HHHHh | 0 ~ fffff | Data area-bit (M) |
| B | T | HHHHh | 0 ~ fffff | Timer (T) |
| B | R | HHHHh | 0 ~ fffff | Internal output (R) |
| B | L | HHHHh | 0 ~ fffff | Link area-bit (L) |
| W | TC | HH | 0 ~ ff | Timer/Counter current value |
| W | WM | HHHH | 0 ~ 270f | Data area-word (M) |
| W | WX | HHHH | 0 ~ 270f | External input-word (X) |
| W | WY | HHHH | 0 ~ 270f | External output-word (Y) |
| W | WR | HHHH | 0 ~ 270f | Internal output-word (R) |
| W | WL | HHHH | 0 ~ 270f | Link area-word (L) |
Wiring Diagrams
NOTE: The serial port pin assignments may vary between HMI models.
Diagram 1: RS-232 (EH-SIO port 1 / port 2)
| HMI | Direction | PLC |
|---|---|---|
| Pin assignments | RS232 8P RJ45 Male | |
| Rx | ↔ (bidirectional) | 5 |
| Tx | ↔ (bidirectional) | 6 |
| GND | ↔ (bidirectional) | 1 |
| CTS | ↔ (bidirectional, optional) | 8 |
| ↕︎ (tie) | 4 7 |
Diagram 2: RS-485 4W (EH-SIO port 2)
The following is the view from the soldering point of a connector.

| HMI | Direction | PLC |
|---|---|---|
| Pin assignments | Hitachi EH-SIO port 2 | |
| Rx- | ↔ (bidirectional) | 2 Tx- |
| Rx+ | ↔ (bidirectional) | 1 Tx+ |
| Tx- | ↔ (bidirectional) | 4 Rx- |
| Tx+ | ↔ (bidirectional) | 3 Rx+ |
| GND | ↔ (bidirectional) | 6 GND |
Diagram 3: RS-485 2W (EH-SIO port 2)
The following is the view from the soldering point of a connector.

| HMI | Direction | PLC |
|---|---|---|
| Pin assignments | Hitachi EH-SIO port 2 | |
| Data- | ↔ (bidirectional) | 2 Tx- 1 Tx+ |
| Data+ | ↔ (bidirectional) | 4 Rx- 3 Rx+ |
| GND | ↔ (bidirectional) | 6 GND |
