An STO fault (fault 1018 on the touchscreen) tells you that the STO terminal is OPEN. We utilize this terminal at MacroAir for our fire alarm function. The terminal is designed to be closed with the P24 terminal. The fan will not operate at all until this terminal is closed and the fault code is clear. Below are some possible causes for an STO code.
1. Orange and orange/white wires are not shorted together. For standard touchpads, we heatshrink the two wires together inside the touchpad enclosure. For Controller 30s, the wires need to be twisted together by the installer. For AirLynk, a terminal block is located on the outside of the AirLynk panel with a jumper in it. If a fire alarm is not being used, ensure that one of these methods is being used. More information on fire alarm wiring can be found here.
2. The wrong type of relay is being used. The relay must be normally-closed. It cannot be normally-open.
3. The fire alarm has been activated and the relay is open. If a normally-closed relay is tied into the system, have someone from the fire alarm company ensure that the relay is in the correct closed position.
4. The CAT5 cable is out of spec or damaged. CAT5e shielded stranded minimum must be used. Replace any damaged or out of spec cable with the proper cable.
5. The incorrect CAT5 pinout is used. All of our CAT5 connections require a 568B pinout.
6. The orange and orange/white wires are not tied into the correct VFD terminals. Ensure that they are landed on STO and P24.
7. The fire alarm wiring is tied between different model fans. You cannot use a fire alarm between different drive types, such as Schneider, Yaskawa, etc. There must be a separate relay for each drive type.
8. Noise/Electrical interference. The communication signal can degrade if the CAT5 is ran too close to the fan's incoming power or other high voltage (120VAC and up) wiring. Ensure that the CAT5 wiring is ran at least 6" away from any power wires. The further away, the better. Never run CAT5 and power wiring in the same conduit. Cat5 cannot be coiled and any excess must be cut or ran in a method that eliminates any coils.
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