Rockwell Automation 1764-xxxx MICROLOGIX 1500 PROGRAMMABLE CONTROLLERS User Manual

Page 146

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Publication 1764-UM001B-EN-P - April 2002

E-14 Understanding Communication Protocols

Refer to the MicroLogix 1200 and MicroLogix 1500 Programmable
Controllers Instruction Set Reference Manual
, publication 1762-RM001
for detailed configuration information.

When the driver is set to ASCII, the following parameters can be
changed:

Table E.4 ASCII Channel Configuration Parameters

Parameter

Description

Programming
Software Default

Baud Rate

Toggles between the communication rate of 300, 600, 1200, 2400, 4800, 9600, 19.2K, and 38.4K.

1200

Parity

Toggles between None, Odd, and Even.

None

Termination 1 Specifies the first termination character. The termination character defines the one or two character

sequence used to specify the end of an ASCII line received. Setting the first ASCII termination
character to undefined (\ff) indicates no ASCII receiver line termination is used.

\d

Termination 2 Specifies the second termination character. The termination character defines the one or two

character sequence used to specify the end of an ASCII line received. Setting the second ASCII
Termination character to undefined (\ff) and the first ASCII Termination character to a defined value
(\d) indicates a single character termination sequence.

\ff

Control Line

Toggles between No Handshaking, Half-Duplex Modem, and Full-Duplex Modem

No Handshaking

Delete Mode

The Delete Mode allows you to select the mode of the “delete” character. Toggles between Ignore,
CRT, and Printer.
Delete Mode affects the characters echoed back to the remote device. When Delete Mode is
enabled, the previous character is removed from the receive buffer.

In CRT mode, when a delete character is encountered, the controller echos three characters
to the device: backspace, space, and backspace. This erases the previous character on the
terminal.

In Printer Mode, when a delete character is encountered, the controller echos the slash
character, then the deleted character.

Enable the Echo parameter to use Delete Mode.

Ignore

Echo

When Echo Mode is enabled, all of the characters received are echoed back to the remote device.
This allows you to view characters on a terminal connected to the controller. Toggles between
Enabled and Disabled.

Disabled

XON/XOFF

Allows you to Enable or Disable XON/ XOFF software handshaking. XON/XOFF software handshaking
involves the XON and XOFF control characters in the ASCII character set.
When the receiver receives the XOFF character, the transmitter stops transmitting until the receiver
receives the XON character. If the receiver does not receive an XON character after 60 seconds, the
transmitter automatically resumes sending characters.
Also, when the receive buffer is more than 80% full, an XOFF character is sent to the remote device
to pause the transmission. Then, when the receive buffer drops to less than 80% full, an XON
character is sent to the remote device to resume the transmission.

Disabled

RTS Off
Delay (x20
ms)

Allows you to select the delay between when a transmission is ended and when RTS is dropped.
Specify the RTS Off Delay value in increments of 20 ms. Valid range is 0 to 65535.

0

RTS Send
Delay (x20
ms)

Allows you to select the delay between when RTS is raised and the transmission is initiated. Specify
the RTS Send Delay value in increments of 20 ms. Valid range is 0 to 65535.

0

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