Table of Contents
RS422 RS485
The ZSOM-Control and the ZSOM-Mini each provide one RS422/RS485 interface. By default it works as full-duplex RS-422 (4-wire); with two solder bridges or wiring at the terminals it can be used as half-duplex RS-485 bus (2-wire).
Features
| ZSOM-Control | ZSOM-Mini | |
|---|---|---|
| Number of interfaces | 1 | 1 |
| Default mode | RS-422 full duplex (4-wire) | RS-422 full duplex (4-wire) |
| RS-485 (2-wire) | via terminals or solder bridges JP2/JP3 | via terminals or solder bridges JP3/JP4 |
| Baud rate | up to 460800 | up to 460800 |
| Termination 120 Ω (receiver pair) | jumper JP1 | jumper JP2 |
| Fail-safe biasing | 2.2 kΩ on both pairs | 2.2 kΩ on both pairs |
| Bus load | 1/8 unit load (up to 256 nodes on one bus) | 1/8 unit load (up to 256 nodes on one bus) |
| ESD protection | yes | yes |
| Terminals | TX+ 54, TX- 55, RX- 56, RX+ 57, GND 53/58 (pinout) | TX+ 21, TX- 20, RX- 19, RX+ 18, GND 17/22 (pinout) |
RS-422 (4-wire)
- Connect TX+/TX- of the ZSOM to RX+/RX- of the device and RX+/RX- of the ZSOM to TX+/TX- of the device. Connect GND.
- Mount the termination jumper if the ZSOM is at the end of the line.
RS-485 (2-wire)
- Connect TX+ with RX+ and TX- with RX-, either at the screw terminals or with the solder bridges (“Duplex”) on the back of the board. The solder bridges are open by default.
- Terminate the bus only at its two ends (120 Ω). Mount the termination jumper only if the ZSOM is at one end of the bus.
- Note: the naming of the RS-485 lines (A/B, +/-) differs between manufacturers. If no communication is possible, swap the two lines.
| ZSOM-Control | ZSOM-Mini |
 |  |
Usage in LabVIEW
The interface is a serial port of NI Linux Real-Time and is used from RT code with the NI-VISA serial functions. In RS-485 2-wire mode, switching the transmit direction is handled by VISA; the wire mode is set with a VISA property node.
See the examples included in the SDK:
- ZSOM-Control: ZSOM-Control-Serial.lvproj
- ZSOM-Mini: ZSOM-Mini-ALLIO.lvproj
