Digital Loggers

DLI Power Controller Serial Port Usage

 Serial I/O differs for each product:

External I/O

External ports are useful for rebooting or configuring servers and routers, controlling modems, etc.  Serial ports connect to a web terminal which is started by clicking the "Console" button below. External 9-pin  RS-232 ports are "three wire" configuration with the DSR, CTS and DTR handshaking lines tied together.

Db9 Serial Cable Pinout

Internal I/O

Internal TTL ports are used for factory option boards (like the PoE voltage monitor) and custom hardware provided by customers or DLI.  Customers have used this port to connect to temperature sensors, Arduino/Galileo controllers and other devices.  You may output to the port via a script (possibly triggered by Auto-Ping, or you may interact using the web terminal .  Use your imagination.  Here are examples of a temperature sensors used by our customers (sensor output is 3.3V TTL):

The location of the main TTL port marked J5 on the control board is pictured below.  This is an unkeyed 2mm 4-pin header.


Connect to the internal port at your own risk.  Serial ports do not require handshaking. Internal TTL ports are 3.3V ONLY.  Although you may use the second pin to obtain 5V ~100mA to power your device, DO NOT  apply +5V to SIO_IN = RDXO.  This will latch-up the processor, potentially damaging the control board.

Firmware versions 1.4.x and later support serial port control via the built-in scripting language.  For example:

PRINT - Sends a string ($) to the serial Port 1.
PRINT2- Sends a string ($) to the serial Port 2.
PRINT (ATDT4083305599) - Sends a string to dial a mode

Using the Console port, you can remotely control and monitor devices, VT-52 style.
Firmware versions 1.5.0 and later also support web terminal access.  Clicking on the Console link link will spawn a web terminal with bi-directional access to the port.  Enter "\n" to transmit a carriage return.  Interactivity of the serial terminal windows has been improved in versions 1.6.7 and later.

Port baud rates and modes can be manually configured on the SCRIPTING page:

The command MODE NNN selects the serial port mode.

To use an external serial port, no mode changes are required. To customize serial port function, the port mode is set by a single control byte. The correct byte value is the sum of these binary flags:

  • 1 - Serial port 1 echo
  • 8 - Serial port 2 echo
  • 2 - Cross connect port 1 to port 2
  • 4 - Cross connect port 2 to port 1
  • 16 - Supply power to an or other line-powered device connected to port 1
  • 32 - Supply power to a temperature sensor or other line-powered device connected to port 2

For example, MODE 1 would set echo on serial port 1 only.  MODE 49 would provide echo on port 1 and provide power to both ports, ie. 9=1+16+32

For general information on RS-232 communications, this wiki may be helpful.

A single serial port may be expanded to control 20 devices using a DLI serial switch.

Questions, suggestions?