Appendix E. RF400 Series Port Pin Descriptions

RS-232 Port

The “RS232” port is a partial implementation of RS-232C. It is configured as

Data Communications Equipment (DCE) for direct cable connection to Data

Terminal Equipment (DTE) such as an IBM-PC serial port.

RS-232CONNECTOR, 9-PIN D-SUB FEMALE

PINI/ODESCRIPTION

 

 

 

1

 

 

2

O

TX

3

I

RX

4

 

 

5

 

GND

6

 

 

7

 

 

8

O

CTS

9

 

 

I = Signal Into the RF400, 0 = Signal Out of the RF400

Only CTS is implemented for flow control. If data arrives (say from a PC) faster than the RF400 transmits it, the RF400 will de-assert CTS when the 640 byte port buffer is full. If the PC continues to send data, the buffer will accept it and may wrap around over-writing oldest data. PC208W and LoggerNet monitor CTS to prevent buffer over-run.

The RF400 can transmit RF packets slightly in excess of 9600 baud. When RF packets are received by the RF400, that data is immediately sent to the “active interface” port without flow control (no RTS).

For many applications the RF400 works fine with no flow control. The need for flow control arises when longer standby modes are used, where more data could be sent than the 640 byte buffer can hold before transmittal. For example, if the RF400s are in Standby Mode 6 (see Appendix D), an RF400 needs to buffer incoming RS-232 data for up to 8 seconds while waiting for the other RF400 to wake up before transmitting it. Also, if the RF400 is doing a lot of retries, that can take extra time and require flow control to avoid buffer over-run.

CS I/O Port

The CS I/O port is Campbell Scientific's input/output port. It is not a standard RS-232 pin-out. The following table provides pin-out information on the port when connected to a datalogger.

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