GE 90-30/20/Micro manual Read/Write Data Function #3

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Read/Write Data (Function #3)

The read/write function reads a word of extra status data from a module specified in the parameter block, then writes a data value between 0 and 15 from the parameter block to that module. This read write process is repeated for each module in a list in the parameter block. The parameter block (N * 3) + 3 words of reference memory, where N is the number of modules with which data will be exchanged.

Location	Field	Meaning
Address	Function	3 = read/write
Address + 1	Error Code	An error code is placed here if the function fails because
		any of the modules is not present, inappropriate, or not
		working. No error code is set if the function executes but
		any of the modules does not receive the write data
		properly
Address + 2	First rack & slot	Rack and slot number (in the form RRSS in hexadecimal,
		where RR is the rack number and SS is the slot number)
		of the first module with which data will be exchanged
Address + 3	Read data from	The data read from the first module will be placed here
	first module
Address + 4	Write data for	This data value will be written to the first module
	first module
Address + 5	Second rack &	Rack and slot number (in the form RRSS in hexadecimal,
	slot	where RR is the rack number and SS is the slot number)
		of the second module with which data will be exchanged
Address + 6	Read data from	The data read from the second module will be placed here
	second module
Address + 7	Write data for	This data value will be written to the second module
	second module
Address + ((I-1) * 3) + 2	Ith rack & slot	Rack and slot number (in the form RRSS in hexadecimal,
		where RR is the rack number and SS is the slot number)
		of the Ith module with which data will be exchanged
Address + ((I-1) * 3) + 3	Read data from	The data read from the Ith module will be placed here
	Ith module
Address + ((I-1) * 3) + 4	Write data for	This data value will be written to the Ith module
	Ith module
Address + ((N-1) * 3) + 2	Last rack & slot	Rack and slot number (in the form RRSS in hexadecimal,
		where RR is the rack number and SS is the slot number)
		of the last module with which data will be exchanged
Address + ((N-1) * 3) + 3	Read data from	The data read from the last module will be placed here
	last module
Address + ((N-1) * 3) + 4	Write data for	This data value will be written to the last module
	last module
Address + (N * 3) + 2	End of list	A zero in this word indicates the end of the list of modules
	indicator

4-168 Series 90-30/20/Micro Programmable Controllers Reference Manual–September 1998 GFK-0467K