---
title: "Connection"
canonical: "https://docs.cuesystem.com/space/RUM/489455631/Connection"
format: markdown
---
The enclosure of relayCUE-8 allows simple installation into the switchboard on the DIN rail.
# Power, input, and output connection
Eight digital contact closure inputs are connected via two 8-pin connectors Phoenix 3,5 mm. Every input has 2 terminals – the first is input signal, the second is input common (ground).
Eight relays are connected via a screw-type terminal (up to 1.5 mm2 wire). Four relays have two terminals C-NO (Common – Normally Open), 230 V, max. 10 A (resistive load), and four relays have three terminals NC‑C‑NO (Normally Close – Common – Normally Open), 230V, max. 10A (resistive load).
AC Power input is connected via four screw-type terminals (up to 1.5 mm2 wire). Two terminals are L (Live), and two terminals are N (Neutral). A connection of the relays, power, and contact closure inputs is described in the picture below.
All relays are open in the following picture:
> 📝 **Important note:**
> 📝
> 📝 The relay contacts in relayCUE-8 are constructed for resistive load up to 230V/10A. If these relays are used for the switching of inductive (or capacitive) loads, voltage or power peaks can occur, which may exceed these parameters even if the load has the stated take-off lower than 230V/10A. We therefore do not recommend using relayCUE-8 for switching inductive or capacitive loads with take-off higher than 400W.
> 📝
> 📝 If you need to switch higher loads, use contactors. Unlike relays, contactors are designed with features to control and suppress the arc produced when interrupting inductive load currents. You can then use the relay of the relayCUE-8 unit to control the coil of this contactor.
# RS-485 port connection
The relayCUE-8 control port is compatible with RS-485 standard and so it is to be installed on controller serial ports which are compatible with this standard or the RS-232/RS-485 converter must be used. Serial port RS‑485 is connected via 5-pin connector Phoenix 3,5 mm.
A typical connection of RS-485 port is shown in the following picture:
relayCUE-8 can also be connected via supplied cable CA0183 and PEbus cable adapter GP0045, see picture below. Other “Power Express”(PEX) units can also be connected to this bus.
> 📝 **Important Note: **
> 📝
> 📝 If relayCUE-8 and PEX units are to be combined on the same bus, the PEX units must be installed and programmed using their serial drivers on serial port like any other serial controlled equipments (similar way like the relayCUE-8) and not by using “Insert Local Panels and Interfaces” wizard!
For connection of cable CA0183, see [https://cue.atlassian.net/wiki/spaces/RUM/pages/488276029](https://cue.atlassian.net/wiki/spaces/RUM/pages/488276029)
> 📝 Note:
> 📝
> 📝 Max. 31 units (relayCUE-8 or any PEX unit) can be connected to one serial port on ipCUE compatible with RS-485 standard.
# IR/SERIAL port connection
In some installation where the proper serial ports are not available and where there is no need to use the status-reading commands, it is possible to control relayCUE-8 from IR/SERIAL one way communication port.
The cable for connection to IR/SERIAL port needs two wire connections, see picture below:
> 📝 **Please pay attention to the following notes when using this type of installation:**
> 📝
> 📝 1. cable for this connection is : pin 1 on IR/SERIAL connector on ipCUE is connected to pin 2+3 on SERIAL port connector on relayCUE-8 and pin 2 on IR/SERIAL connector on ipCUE is connected to pin 1 on SERIAL port connector on relayCUE-8.
> 📝 2. only one relayCUE-8 unit can be driven from one IR/SERIAL port!
> 📝 3. commands for reading relay or input statuses have no effect !