CDR-3250/80 TECHNICAL MANUAL
Issue 2.2
2-5
Table 2-2 Serial Remote Control Bus Connector (J4) Pin Descriptions-Cont.
NOTE (CONT):
The Request to Send (RTS) and Clear to Send (CTS) handshake circuits are generally not used when the line drivers are
configured for bus sharing operation. When the line drivers are not configured for bus sharing, the operation of the CTS and
RTS lines is as follows: When a receiver is ready to accept remote control commands it will set the RTS circuit true. When
it has received a message and is processing the commands, it will set the RTS circuit false until it is ready to receive another
command. The receiver will only transmit messages to an external device when its CTS circuit is held true by the external
device. The external device may stop the transmitted output of the receiver (to prevent buffer overflow for example) by
taking the CTS circuit false. When the CTS circuit is again taken true, the receiver will begin transmitting where it left off.
NOTE: When bus sharing is enabled from the receiver front panel, the state of the CTS circuit is ignored.
The number of CDR-3200 series receivers that may be connected to a single controller is dependent on the serial bus type
and the line driver characteristics of the controller, but in general is at least 10 receivers for RS-232 operation and at least
30 receivers for RS-422 operation. Dual chassis models count as two receivers. The input resistance of the RS-232 line
receivers is approximately 5000 Ohms. The CDR-3250/80 receiver contains no termination resistors for the RS-422 bus.
If connected directly to a computer interface also configured as DTE, a reversal of transmit and receive data (TXD and RXD
or SD and RD) and request to send and clear to send (RTS and CTS or RS and CS) lines may be necessary. The Request
to Send and Clear to Send lines may be jumpered together on the mating connector if required by the system. These
reversals or jumpers are normally not required if units are connected through a modem. If a CDR-3200 series receiver is
to be connected to another DTE device as its controller, the circuits must be swapped for proper operation as follows:
CDR-3200 Series Receiver
Other DTE Device
Transmitted Data
---------->-----------
Received Data
Received Data
----------<-----------
Transmitted Data
Request to Send
---------->-----------
Clear to Send
Clear to Send
----------<-----------
Request to Send
Signal Ground -----------------------
Signal
Ground
CAUTION: Refer to note below EEPCLR command in table 3-5.
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