Bio-Rad Model 550, Ultramark, and Benchmark Microplate Reader Accessories - Manual (Page 35)

7.2 RS-232 Interface Specifications
The following specification describes the syntax and language required for computer con-
trol of the reader. In addition, the Model 550 reader will perform passive unidirectional data
transmission. The instrument will automatically transmit the data in ASCII code after each
reading if it is properly connected to a host computer. See the “RTPLATE” command for an
example of ASCII output.
Note: This automatic output will be of Measurement O.D. minus Reference O.D. when
in Dual Wavelength mode (i.e. only one set of 96 numbers).
1. SIGNALS
TXD: transmit data
RXD: receive data
DTR: data terminal ready
DSR: data set ready
CTS: clear to send
RTS: ready to send
SIGNAL GROUND (SHIELD GROUND to hood / chassis ground)
2. TRANSMISSION
Baud rate 9600
Data width 8
Stop width 1
Parity None
3. DATA
All data must be transmitted in ASCII.
The READER command interpreter must be “case blind” (no distinction between
upper or lower case ASCII characters).
All READER commands can be distinguished from each other by the first two
characters of the command.
4. SIGNAL ASSIGNMENT
Pin # READER Signal type Host Signal Pair
1 SHIELD GROUND SHIELD GROUND
2 TRANSMIT DATA RECEIVE DATA
3 RECEIVE DATA TRANSMIT DATA
4 REQUEST TO SEND CLEAR TO SEND
5 CLEAR TO SEND REQUEST TO SEND
6 DATA SET READY DATA TERMINAL READY
7 SIGNAL GROUND SIGNAL GROUND
20 DATA TERMINAL READY DATA SET READY
Shield ground 1
Transmit data 2
Receive data 3
Data set ready 6
Signal GND 7
Data terminal ready 20
Clear to send 5
Request to send 4
32
Host
Computer
Model 550
Reader