RD Controls Hardware Release Note 20.0 <P> CAMAC C1013 Module <P> Cryogenic Thermometer Interface

RD Controls Hardware Release Note 20.0

CAMAC C1013 Module

Cryogenic Thermometer Interface

R. West

February 11, 1991


The C1013 CAMAC module collects data from a cryogenic thermometer connected to the module via its RS232 interface. The data obtained from the meter is pooled in the module's dynamic memory and may be selectively read by issuing CAMAC commands using the EPICURE Beamline Control System. The only device the C1013 module presently supports is a Lake Shore Cryotronics, Inc., model 820 cyrogenic thermometer with dual input cards and an 8229 scanner conversion card.

Module Configuration

The C1013 module is based on the CAMAC 1111 single board computer:

On the front panel of the module are the following buttons and indicators:

RS232 Interface Configuration

The C1013 module has an RS232 I/O port on the rear of the module and also on the front. Each port's baud rate may be set to a value from 300 to 19200. The I/O connector for the rear port has 8 switches which are used to indicate the type of device connected to the C1013 module. Switches 1 through 4 indicate the type of the connected meter and switches 5 through 8 indicate the baud rate. For the C1013 module, switch 2 and switch 6 both in the ON position indicate a 1200 baud cryogenic thermometer is connected. Any other switch configuration is invalid.

The switches on the cryogenic thermometer must be set so its RS232 interface has the following characteristics:

Lake Shore Cryotronics, Inc., Model 820 Cryogenic Thermometer

The C1013 module has total control of all meter functions and exchanges ASCII strings in a request/reply fashion. The C1013 module transmits a request to the meter which consists of a string of ASCII characters terminated by an end-of-line (EOL) sequence. The EOL terminator sequence for both sending and receiving is a carriage return, line feed pair. If data is requested, the meter outputs it immediately upon receipt of the EOL sequence. A temperature reading has the following format:


The cryogenic thermometer is equipped with dual sensor inputs, A and B. The optional 8229 Scanner Conversion unit expands the A input to handle five sensors which are designated as A0 through A4. The C1013 module reads each of these six sensors once every four seconds. Each ASCII string read from the meter is converted to a binary value which is pooled in memory to be read by the appropiate CAMAC command. The four second time interval is the maximum amount of time the meter requires to obtain a valid reading.


The cryogenic thermometer cannot be setup to periodically output data values over its RS232 interface. Therefore, the C1013 module must write ASCII command strings to the meter to obtain the necessary reading and status information. This section lists these command strings. Unless otherwise noted, the module delays one-half second after reading a response to a command string before writing the next command string.

This command sequence is repeatedly executed by the C1013 module. One execution of the entire sequence requires approximately 40 seconds.

CAMAC Functions

When a CAMAC operation is performed, the Z8002 processor executes a vectored interrupt to a routine which reads the CMCSLV data lines and determines the function code. A jump is then executed to the appropriate routine to process the request.

Function Code Descriptions

Data Format

The C1013 module converts the ASCII text string from the connected meter to a signed 32-bit integer representing the floating point data value times 10 to the 6th power.


Diagnostic commands may be directly input to the module by connecting a computer terminal to one of the RS232 ports. A HELP menu displays the commands which are available to assist in trouble shooting. The following commands can be executed at a terminal:

Status LEDs

Security, Privacy, Legal