Wind Speed Direction Switch (With USB and RS-485 Modbus communication output along with analog voltage or current output)

Introduction

This Ocean Controls KTA- 250 and Davis 6410 combination is a stand alone anemometer monitoring and alarming solution. It allows the wind speed and direction to be measured without the need for the entire weather station. Monitoring of the wind speed and direction can be done via the analog retransmission channels with 0 20mA or 4 20mA outputs. As well as monitoring the speed and direction, there are 2 on board alarm relays can be programmed to activate at a certain speed or wind direction, or combination of the two. Wind speed and direction can also be monitored using the Modbus protocol with either a USB or 2 wire RS485 connection.

Software

Ocean Controls supplies a software configuration package called “KTA250 Configurator” which is a simple to use windows based program. The configuration software allows the user to monitor the wind speed and direction, as well as the maximum and minimum speeds, and allows the user to set all the available settings. The value by default is Km/H, but can bechanged to MPH with a value of 0, Knots with a value of 2 or m/sec with a value of 3, all other values are MPH.  When the units are set, all parameters to do with wind speed are displayed in these units and the maximum and minimum speeds are reset.

Analog Re-Transmission
The KTA-250 can transmit the wind speed and direction as an analog voltage (0-5V or 1-5V) or current signal (0-20mW or 4-20mA) for both wind speed and direction.

Current Calibration and Direction Offset

If the anemometer can not be mounted so that the sensor is facing north, or the user does not wish to manually adjust the sensor, a direction offset can entered to holding register 34 and then this value is added to all direction readings. If the user wishes to check the calibration of the current loop transmission a value of 1 should be written to holding register 36. This will output the 20mA level to both current channels. If it needs to be adjusted, remove the lid of the KTA 250 case and then a current sensor should be connected to each output and the trimpots near U1 (Channel 1) and U2 (Channel 2) can be adjusted until exactly 20mA is displayed on the current sensor. Once a satisfactory calibration has been achieved, holding register 36 should be written back to 0.

Alarms

There are two alarm relays on the KTA 250, each relay can be activated by either the wind speed going over a certain limit or the direction being within a certain range, or a combination of the two. The levels and time limits that control the alarms are set using the software or through the Modbus holding registers. Alarm 1 settings begin at holding register 10 and alarm 2 settings begin at holding register 20. Holding register 10 enables alarming on wind speed, register 11 is the speed above which the alarm wil l become active if it has been above that point for the number of seconds defined by register 12. Register 13 enables alarming on wind direction. The direction must be less than register 14 and greater than register 15 for the time defined by register 16, to activate the alarm. If register 17 is 0, either speed or direction will activate the relay when the limit is reached, but when register 17 is 1, both the speed and direction alarms must be active for the relay to turn on. Alarm relay 2 has the same functionality as alarm relay 1, except the registers associated with it are 20-27 as opposed to 10-17 for Alarm 1.