About the 8020-SCP-523
8020-SCP-523 is a Model 500, 8K Processor with RAM that is manufactured by Square D. The miscellaneous errors are represented by the 29000-29999 range. When the last three numbers are 500, the number of assigned local interface registers must be at least 8 for 1 defined channel and 12 for 2 defined channels. When the last three numbers are 501, the local interface control registers are insufficient. The processor communication port errors are represented by the 01000-09999 range. The third and fourth numbers in the error number indicate the error description. 11 is a communications overflow. 12 is a buffer overflow. 13 means illegal data. 14 means a wrong reply (odd/even). 15 is a checksum error. 16 is a framing error. 17 is a parity error. 18 indicates an inability to communicate through Port #P. 19 means a the user must retry the timeout. The general errors are represented by the 00001-00999. 960 means a HALT or HALT/RUN bit set. 965 is an illegal internal error code. 970 means that the scan time of the processor is greater than 1 second, or that the scan limit in S8167 has been exceeded. 979 means that rack addressing is missing. 980 means that the keyswitch is in RUN mode, but there is no program in the processor memory. 981 means that a PROM inhibit coil is not in the memory. 983 means that a safeguarding rung is not in the memory. 984 means that an undefined register is programmed in user memory.
