GE PACSystems RX7i, Reference Manual

Page: 263 / 317

Chapter 6. Serial I/O, SNP & RTU Protocols
252 PACSystems* RX7i, RX3i and RSTi-EP CPU Reference Manual GFK-2222AD
6.3.4 RTU Scratch Pad
The entire scratch pad is updated every time an external READ request is received by the PACSystems
RTU slave. All scratch pad locations are
read onl y. The scratch pad is a byte-oriented memory type.
RTU Scratch Pad Memory Allocation
SP Address Field Identifier
Bits
7 6 5 4 3 2 1 0
00 CPU Run Status 0 0 0 0 See note.
88
01 CPU Command Status Bit pattern same as SP(00)
02
03
CPU Type
Major
89
(in hexadecimal)
Minor
90
(in hexadecimal)
04 – 0B CPU SNP ID 7 ASCII char termination character (00h)
0C
0D
CPU Firmware Revision No.
Major (in BCD)
Minor (in BCD)
0E
0F Communications Management Module
(CMM) Firmware Revision No. Major
Minor
10 — 11 Reserved 00h
12 Node Type Identifier PACSystems 43 (hexadecimal)
13 — 15 Reserved 00h
16 RTU Station Address 1 — 247 (decimal)
17 Reserved 00h
18 — 33
91
Sizes of Memory Types
18 — 1B Register Memory %R size (words)
1C — 1F Analog Input Table %AI size (words)
20 — 23 Analog Output Table %AO size (words)
24 — 27 Input Table %I size (bits)
28 — 2B Output Table %O size (bits)
2C — 2F Internal Discrete Memory %M size (bits)
30 — 33 User Program Code
The amount of program memory occupied by the logic
program.
34 — FF Reserved 00h
88
0000 = Run_Enabled 0100 = Halted 0001 = Run_Disabled
0101 = Suspended 0010 = Stopped 0110 = Stopped_IO_Enabled
89
CPU Major Type Codes: PACSystems 0x43
90
PACSystems Minor Types for CPU: refer to Message (17): Report Device Type
91
Four bytes hold the hexadecimal length of each memory type with the most significant word reserved for future expansion.
For example, the default register memory size of 1024 words (0400h) would be returned in the following format:
Word Least Significant Most Significant
SP Byte 18 19 1A 1B
Contains 00 04 00 00