User manual

1-Wire Application Guide v1.04 Page 27 of 41
4 Environmental Sensors
4.1 Relay Driver
Midon Design offers 2 types of 1-Wire relay drivers.
1. 1WIO, which has 4 SPDT relays, and
2. MD3020G, which has one SPDT relay.
The 1WIO is DS2408 based and up to 40 of these devices are supported on
TEMP08. When using the 1WIO in relay mode (it is also available as an input
device), make sure to turn off input sensing by the EIN OFF command to avoid
false readings from the DS2408. 1WIO is supported by both TEMP08 and
1WSwitch.
The MD3020G is DS2406 based. It is no longer supported by TEMP08, but was
supported by TEMP08’s sister product, the 1WSwitch.
Relay drivers are useful to interface with non-1-Wire devices that need simple
on/off functionality, such as sprinkler systems, alarm systems, low voltage
lighting, X10 Powerflash interfaces, etc. The relays used on both of these
sensors should not normally be directly connected to mains power for safety
reasons, but can easily be connected to other relays to operate mains powered
devices.
The SPDT contacts provide for Normally Open (NO) and Normally Closed (NC)
contacts. A NO contact is open when power is not applied to the relay, and a NC
contact is closed when power is not applied. Both contacts are referenced to the
Common (C) connection of the relay.
4.2 Contact Sensor
Contact sensors are used to determine the state of a contact. Midon Design
offers the 1WIO as a 4 contact input device. Wiring of the contacts can be done
as shown in Figure 20.
When using the 1WIO as in input device, make sure that you enable the input
functionality by the EIN ON command.