Elmo SERVO AMPLIFIER DBP SERIES Manual Do Utilizador

17

DBP - Rev 6/93

The RS485 in the DCB is configured as 8-bit, no parity, 1 stop bit, half

duplex. The following baud rates are available: 300, 600, 1200, 2400, 4800,

9600, 19200, 38400, 57600. No hardware handshaking is required.

In the RS-485, which is a Half Duplex system, all the Transmitters and all

the Receivers share the same Multidrop wire. Therefore, each character that is

transmitted on the line, is automatically received by all the Receivers. This

is an inherently "confused" way to transmit data and no "Echo" procedure can

assure reliable communication.

In order to solve this reliability problem, it is necessary to use standard

protocols procedures.

It is important to understand that using RS485 with the DCB products without

any protocol is possible. This is also the default condition whenever the RS485

is activated. However, the reliability of the communication is only assured

when activating the protocol. This is done by sending the command CK1 from the

host to the DCB.

Chapter 1.2.1 in the DCB Software manual explains the standard protocol used

and supplied by Elmo.

The analog part of the DBP is actually a standard amplifier that operates in

current mode. However, the DCB receives continuously analog information about

the current magnitude, direction and ripple. This information is processed to

obtain digital control of the following features:

* Continuous current limit

* Peak current limit

* Time dependent peak current limit

* Current ripple