Extron Electronics CTL101 User Manual

Page 25

CTL101 Operation Manual - V1.3 03/22/02

2. Flow Control - The Input Serial Port (host computer) can receive XON / XOFF flow control from
the CTL101. This is beneficial when the host computer is controlling the video equipment
simultaneously with a contact closure and / or IR signal.

If a contact change or an IR signal is sensed, the CTL101 will send an XOFF command to the
computer (once a delimiter is received from the computer going to the equipment, or a one second
timeout). This allows the computer to stop transmitting command messages without overflowing
the 32 byte FIFO in the CTL101 receive buffer. The CTL101 will trap the response message
from the video equipment in response to the last command from the host computer. At this time
the CTL101 will start sending its programmed command string to the video equipment. After the
CTL101 has sent its command string, an XON will be sent to the host computer indicating it can
resume communication with the video equipment. At this time, the trapped response from the last
host command will be sent to the host computer to verify that the last command was processed.

Note: This feature must be used with the delimiter pause established, otherwise the CTL101 has no
way of knowing when the host computer has ended a command and the video equipment has ended its
response.

Select "3".

Select Full or Half duplex ports.
1. Both ports Full Duplex (Default).
2. Input port Full Duplex & Output port Half Duplex.
3. Input port Half Duplex & Output port Full Duplex.
4. Both ports Half Duplex.
5. Display current.
6. Exit.

3. Full or Half Duplex Ports - For RS-232 operation, full duplex communication is selected. In RS-
422 / RS-485, either full or half duplex communication can be selected.

In half duplex mode and computer control, the driver turns on as each character is transmitted,
and the character is sent without any flow control provided by the CTL101. To prevent
contention, the controlled equipment and the host computer system must provide some means of
flow control. Typically, the host computer would send a command, shut its driver off, and wait
for a response from the controlled equipment before sending the next command. The CTL101
acts as a relay unit between the computer and controlled equipment.

When the CTL101 sends commands in half duplex mode for IR remote control or contact
switches, it automatically activates its driver for each command character transmitted. The
CTL101 uses the end delimiter responses to determine when it can send the next command in a
string. If no end delimiters are detected within one second, it will automatically send the next
command.

DELIMITER PAUSE

If DELIMITER PAUSE is selected, type "4" followed by ENTER. The next series of menus will look
like this.

Select Delimiter Pause.
1. Don’t wait for response.
2. Wait for response between commands.
3. Display current.
4. Exit.