Forma Scientific, Inc.________________________________________________Installation
2-5
• After entering the four digit Access Code, press the ENTER key and "CAL" will
appear in the window.
• Press the DOWN ARROW key.
The Enviro-Scan monitor is now deactivated (placed in a sleep mode) until
electrical power is restored.
2.9 RS-232 Output Interface
The 8500 series freezers are equipped with an RS-232 Serial Communication
Interface for the remote transmission of sensor data. A standard DB-25S connector is located
on the rear of the compressor housing. The data is "dumb printer" formatted, which permits
interfacing with either a computer or a serial printer.
Three wires are used for the RS-232 interface:
1) TX Data = Pin 2
2) RX Data = Pin 3
3) Signal Ground = Pin 7
The data format is seven-bit ASCII with a leading zero (8th bit). Each character is
transmitted with one start-bit, eight data-bits, and two stop-bits, totaling eleven bits. NO
parity-bit is included. Baud rate is 1200.
A data transfer sequence is transmitted according to the following format. X refers
to the variable numerical temperature data.
(NUL) (-) XXX (SP) C (SP) (OVERTEMP) (SP) (LF) (CR) (EOT) (SP) (UNDER TEMP )
The words "OVERTEMP" or "UNDER TEMP" are transmitted with the temperature
if one of those conditions exists at the time the data is transmitted. When there is no alarm
condition, spaces will be sent instead so that there is always a total of 20 characters sent.
SP - space
LF - line feed
CR - carriage return
EOT - end of text
NUL - null character (00)
The Enviro-Scan Monitor transmits temperature and alarm condition data when
power is first applied to the Monitor and then once every hour.
The Enviro-Scan Monitor responds to two ASCII commands from the remote:
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