Overview

The communication protocol used by Cryopad to communicate with 700 series controllers is published here to allow users to integrate an Oxford Cryosystems device into custom control systems.

The 700 series controller incorporates an RS232 interface allowing communication with a remote computer. The communications fall into two categories. 

• The controller  issues 'status packets' at regular (1 second) intervals. The status packets are of a fixed length and format.
• The controller listens for 'command packets' sent by the remote computer. These are small, variable length packets sent by the remote computer to the controller. If the packet contains a valid command, then the controller will immediately act upon that command, potentially over-writing any existing command. In order to determine whether a command has been received and acted upon the remote computer must monitor the information contained in the status packets. Likewise, the status packets should be monitored to determine when the command is complete.

Protocols

For a detailed description of the status packets click status packet protocol, for command packets click command packet protocol.

Wiring

700 series controllers are shipped with a suitable connecting wire, the details of which are illustrated here. 

Serial line settings

700 series controllers use the following R232 settings: 9600 baud, no parity, 1 stop bit.