Data Sheet

Communication Protocol Description

Advanced Digital Motor Controller User Manual 155

Character Echo

The controller will echo back to the PC or Microcontroller every valid character it has re-

ceived. If no echo is received, one of the following is occurring:

• echo has been disabled

• the controller is Off

• the controller may be defective

Command Acknowledgment

The controller will acknowledge commands in one of the two ways:

For commands that cause a reply, such as a conﬁguration read or a speed or amps que-

ries, the reply to the query must be considered as the command acknowledgment.

For commands where no reply is expected, such as speed setting, the controller will

issue a “plus” character (+) followed by a Carriage Return after every command as an ac-

knowledgment.

Command Error

If a command or query has been received, but is not recognized or accepted for any rea-

son, the controller will issue a “minus” character (-) to indicate the error.

If the controller issues the “-” character, it should be assumed that the command was

not recognized or lost and that it should be repeated.

Watchdog time-out

For applications demanding the highest operating safety, the controller should be conﬁg-

ured to automatically switch to another command mode or to stop the motor (but other-

wise remain fully active) if it fails to receive a valid command on its RS232 or USB ports,

or from a MicroBasic Script for more than a predeﬁned period.

By default, the watchdog is enabled with a timeout period of 1 second. Timeout period

can be changed or the watchdog can be disabled by the user. When the watchdog is en-

abled and timeout expires, the controller will accept commands from the next source in

the priority list. See Command Prioritieson page 154.

Controller Present Check

The controller will reply with an ASCII ACK character (0x06) anytime it receives a QRY

character (0x05). This feature can be used to quickly scan a serial port and detect the

presence, absence or disappearance of the controller. The QRY character can be sent at

any time (even in the middle of a command) and has no effect at all on the controller’s

normal operation.