The Auxiliary CPU board is an accessory board that plugs in the main processor board of your weather station. It provides an additional com port in its standard configuration. One more com port (two on the Aux CPU board for a total of three com ports), two opto-isolated digital inputs and two opto-isolated digital outputs, 64 temperature inputs, one humidity input, one lightning input and one leafwettnes input are available as options.



 

Com ports 2 and 3 operate at 2400 baud, 8 data bits, one stop bit and no parity. Both ports are capable of responding to all single character commands described in Communicating with the WRx located elsewhere in this manual. Binary and calibration commands cannot be use with com 2 or com 3. Com ports 2 and 3 are both DTE devices, meaning that you can plug directly into a serial port of a PC with a straight through cable. (Com 1, on the main board, is a DCE device. A null modem must be used with com1 in order to communicate directly with a PC serial port.)
 

RS-232 Interface

The pin out on the RS-232interface is as follows:
.DE 9 Plug    Header
Pin 1             Pin 1 . . . Data Carrier Detect
Pin 2             Pin 3 . . . Transmit Data
Pin 3             Pin 5 . . . Receive Data
Pin 4             Pin 7 . . . . Data Terminal Ready (must be true to send data)
Pin 5             Pin 9 . . . Signal Ground
Pin 6             Pin 2 . . . Data Set Ready
Pin 7             Pin 4 . . . Request Send
Pin 8             Pin 6 . . . Clear to Send
Pin 9             Pin 8 . . . Ring Indicator
 

There are four optional digital opto-isolated IO ports, two inputs and two outputs. The state of the IO ports may be controlled through one of the three com ports using a PC and TWI_LOG’s F1 routine, or a standard communication package

IO Commands
All commands must be preceded with the character “5”.
0- Turns off all output 1 and output 2.
1- Turns on output 1
2- Turns on output 2.
3- Turns on output 1 and 2.
4- Echoes the current state.

For example, to turn on output 2, press “5” and then “2” within three seconds.

When an IO command is sent and received by the weather station a two character number will be echoed back to the PC monitor. The first character will confirm the output command that was just sent, the second character will report the current state of the two input ports as defined by the following:
0- Both input ports detect an open state.
1- Input 1 detects a closed state.
2- Input 2 detects a closed state.
3- Input 1 and 2 detect a closed state.


For example, if input 1 is closed and the characters “52” are sent to the weather station, output 2 will close and the character “22” will be echoed back to the computer. The first character 2 means that output 2 is closed and the second character indicates that input 2 is closed. To echo back the state of the IO without changing the state, send the characters “54”.

IO Hookup

The pinout on IO terminal block TB4 of the Aux CPU board is as follows:

1-Orange wire, 12vdc+
2- Blue wire 12vdc-
3- Brown wire output 1
4- Green wire output 2
5- White/Orange wire input 1
6- White/Blue wire input 2.

Suggested wiring for a simple switch closure on an output:
For output 1= Blue and Brown
For output 2= Blue and Green

Suggested wiring for a 12vdc output.
For output 1= Orange and Brown
For output 2= Orange and Green

(Please note that these outputs are designed for relays or low current devices that require less than 100ma per output.)

Suggested wiring for IO inputs

For input 1= Blue and White/Orange
For input 2= Blue and White/Blue.

 

As an option, up to 64 low resolution temperature sensors may be connected to the Aux-CPU board. The sensor readings are updated once per minute. They may be brought up on the console display by pressing the select and windchill buttons at the same time thereby entering into extended mode. The temperature sensor number (1 through 64) will be displayed in the time/date window. The temperature value will be displayed in the temperature window. Pressing the min or max key changes the sensor selection. To get out of extended mode press select.


The extended temperature sensors can be accessed through the com ports by using the “X” command. When an upper case X is sent to the com port the instrument responds with ASCII space delimited values for the temperatures.

X command example: 71 45 68 85 29

The first two characters 71 represent the value for extended temperature sensor #1. The second two characters (delimited by a space) is 45 and represents the value for extended temperature sensor#2, etc. The temperature scale is in Fahrenheit if the unit is set in English and it is in Celsius if the unit is in Metric mode.

Extended temperature values are not logged in the weather instrument but are logged by WeatherView. Therefore if you wish to have all your data saved, WeatherView must be running at all times.