======Serial Port Programming======

[[hardware:wattmons:WattmonPRO]] and [[hardware:wattmons:WattmonMEGA]] come with an RS-232 serial interface on pins 7 and 8 and an RS-485 port on an RJ45 connector.  The device is configured by default for RS-232 voltage levels and by using a simple DB9 cable can be connected to any serial device.  For specific devices that require TTL levels, a jumper setting inside the device can bypass the level converter IC and it can thus be used to interface with sensors or other devices at 3.3V DC.

=====Using the RS-232 Serial Port=====

To open the serial port, use the [[uphp:functions:fseropen()]] function. 
The serial port is treated like a file after opening and standard file functions such as [[uphp:functions:fread()]], [[uphp:functions:fwrite()]], [[uphp:functions:fgets()]] and [[uphp:functions:filesize()]] apply.

An example of using the serial port is shown below:
<code php>
<?
  // Open the serial port at 115200 baud in non-blocking mode
  $fp=fseropen(115200,0);
  if (!$fp) {
    print("Serial open failed");
  } else {
    $res=fwrite($fp,"Hello from wattmon");
    if ($res) {
      print("An error occurred while trying to write to the port");
    }
    fclose($fp);
  }
?>
</code>

====Jumper Settings Inside Wattmon====

{{20170318_rs232_mode.png?250|Settings for RS-232 Mode}} < //Settings for RS-232 Mode   //{{20170318_ttl_mode.png?250|Settings for TTL Mode}} < //Settings for TTL Mode//

====RS-232 Cable Connection====

In order to connect to a device you will need to procure a DB9 cable (male or female) and connect it up as shown in the following diagram:
{{20170318_wattmonpro_rs232.png?300|RS-232 DB9 Connection to Wattmon}}

=====Using the RS-485 Serial Port=====

In order to use the RS-485 port, you need to disable modbus polling.  This is done from the Devices > Options > Edit Communication Settings as shown here:

{{20170318_modbus_polling_setting.png?600|Disable Modbus Polling}}

To open the RS-485 port, use the [[uphp:functions:f485open()]] function. 
The RS-485 serial port is treated like a file after opening and standard file functions such as [[uphp:functions:fread()]], [[uphp:functions:fwrite()]], [[uphp:functions:fgets()]] and [[uphp:functions:filesize()]] apply.

An example of using the RS-485 serial port is shown below:
<code php>
<?
  // Open the 485 port at 115200 baud with no parity
  $fp=f485open(115200,0);
  if (!$fp) {
    print("Serial open failed");
  } else {
    $res=fwrite($fp,"Hello from wattmon");
    if ($res) {
      print("An error occurred while trying to write to the port");
    }
    fclose($fp);
  }
?>
</code>

====RS-485 Cable Connection====

Use a standard RJ-45 cable and cut it to connect your RS-485 device to [[hardware:wattmons:WattmonPRO]] or [[hardware:wattmons:WattmonMEGA]].  
^ PIN      ^ Color      ^ Description    ^
| 1,2      | Orange     | GND            |
| 4        | Blue       | D+ / A         |
| 5        | White-Blue | D- / B         |

{{20170318_rj45_connector_pinout.png?450|RJ45 Connection Pinout}}