Specifications

SECTION 6 COMMUNICATIONS
35
“A MANNER OF SPEAKING”
The communication signals supported by Anaheim Automation Indexers are: RECEIVE, TRANSMIT,
CLEAR TO SEND (BUSY), AND REQUEST TO SEND.
The method in which the Computer and the Indexer communicate is as follows: When the computer wants
to send some information, it looks at the CTS (Clear To Send) line. This will inform the computer if the
Indexer is ready to receive information. If a logic LOW is read (meaning it is clear to send), the computer
will send information on pin 3, in which the Indexer will receive on pin 3.
When the Indexer receives data that requires some computational time, it will pull the CTS HIGH meaning
it is not clear to send data.
When the Indexer is ready to send something to the Computer it looks at the RTS signal which will inform
the Indexer that the Computer is busy. If the RTS is low then the Indexer will send information on pin 2,
which will be received by the Computer on pin 2 also.
RTS DEFINED
On the SMC40, there is an option to either enable, or disable the RTS. If RTS is enabled, then the above
description applies. If RTS is disabled, then when the SMC40 wants to send information to the Computer,
it will send it without looking at the RTS line. This is used when the computer does not support the RTS
line.
CTS DEFINED
The CTS line must always be supported. No information should be sent to any indexer unless the CTS
line is low. Otherwise the data sent may be lost, and the indexer could possibly stop communicating.
NOTE: THE SIGNAL NAMES ONLY MAKE SENSE FROM THE POINT OF VIEW OF THE DTE. FOR
EXAMPLE, PIN 3 IS CALLED TD (TRANSMIT DATA) BY BOTH SIDES, EVEN THOUGH THE DTE
SENDS IT AND THE DCE RECEIVES IT.
Pin # Name Description
1 CG Chassis Ground
2 TD Transmit Data
3 RD Receive Data
4 RTS Request To Send
5 CTS Clear To Send
7 0 VDC Signal Ground
TABLE 15: RS232C 25 Pin Connection (computer port)