A Modbus-controlled output board with six relays. It sits on the controller’s RS-485 bus, and the controller reads and switches each relay over Modbus RTU.
Some ratings are not filled in yet. Check the current datasheet before wiring.
Switches six loads, each readable and switchable on its own. Each relay can be named and driven by its own control mode.
|
|
| Interface |
Modbus RTU over RS-485 — see Modbus RTU |
| Default address |
32 |
| Power |
Normally port powered from the controller’s bus supply |
| Relays |
6 |
| Contact rating |
From datasheet — to be filled in |
| Load types |
From datasheet — to be filled in |
| Supply |
24 V DC when port powered from the controller’s bus supply; permitted input range from datasheet — to be filled in |
| Standby power |
From datasheet — to be filled in |
| Operating temperature |
From datasheet — to be filled in |
| Enclosure |
From datasheet — to be filled in |
- The relay contacts may switch line voltage fed from elsewhere in the panel. See Electrical Safety.
- The board has no failsafe timer of its own. While it has power, each relay holds the last state it was commanded, even if the controller stops polling it. Any timeout that turns a relay off has to come from the controller.
- All relays come up off when the board is powered. Removing its supply drops every relay, so cutting the board’s supply is the one sure way to turn every output off.
- Each relay’s state is a single register that reads 0 or 1, so a controller can read back each relay’s state as the board reports it.
¶ Maintenance
- Isolate before you touch it. Turn off and lock out both the board’s own supply and every circuit wired through its contacts — the contacts can be live from elsewhere in the panel. See Isolating Equipment.
- Inspect periodically: check the terminal screws are tight, and look for discolored or melted insulation, scorching around a terminal, or a relay that buzzes or chatters. Any of these means the contact is overloaded or failing; replace the board.
- Test each relay after any change: switch it by hand from the controller and confirm the load starts and stops.
- Check the bus while you are there: RS-485 polarity, screen continuity, and termination at both ends of the segment. See Modbus RTU.
- Replacing the board: isolate, label the load wires relay by relay, swap the board, and set the replacement to the same Modbus address as the old one before restoring power. Then test every relay.
Wiring and configuration live with each controller: