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SMB Interface (Serial Measurement Bus, F/A1500 Only)
The F/A1500 has a SMB interface allowing serial communication with as many as 16
F/A1500 modules using a single RS-232 type serial port from a computer. Using the SMB
interface, AFR, F/A, Lambda, %O
, and module status can be read from each F/A1500
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module. The interface supports auto-detection of the modules.
The figure below shows an example with three F/A1500 modules connected to a computer
(here a PC) using the SMB interface. Each module must have a unique address between 0
and Fh (i.e. 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F) that is set using a switch located
between the two SMB connectors on the F/A1500.
Cable part number 1500A-16 connects the PC to the SMB/PC port of any one of the F/A1500
modules (i.e. it does not have to be the module with address 0), and subsequent F/A1500
modules are daisy-chained using part number 1500A-17 cables.
Communication is 38400 baud, 1 start bit, 8 data bits, 1 stop bit and no parity.
The computer sends a one byte message. The high nibble contains the module address (0 to
Fh) and the low nibble contains the command (0 to Fh).
The F/A1500 module addressed responds (within 1 ms max.) with the byte of data requested.
The command from the PC to the F/A1500 modules and the conversion formulas for the data
from the F/A1500 modules to the PC are given in the following table. The state diagram for
SMB communication is at the back of this instruction manual.
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