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5.11 - Read RAM [U12 Datasheet]

Reads 4 bytes out of the U12's internal memory.

Note: Bytes are read down from the starting address. For example, if you read at address 0x203, then byte 0 comes from 0x203, byte 1 comes from 0x202, byte 2 comes from 0x201, and byte 0 comes from 0x200.

Table 5.11-1.

Command

 

Byte #

Description

0

XXXXXXXX

1

XXXXXXXX

2

XXXXXXXX

3

XXXXXXXX

4

XXXXXXXX

5

01X1XX00 (Read RAM)

6

Most Significant Address Byte

7

Least Significant Address Byte

 

 

 

 

Response

 

Byte #

Description

0

01010000

1

Readback of data byte 3

2

Readback of data byte 2

3

Readback of data byte 1

4

Readback of data byte 0

5

XXXXXXXX

6

Most Significant Address Byte

7

Least Significant Address Byte

Table 5.11-2.

Non-Volatile RAM Map

 

Address Range

Description

0x00

A copy of the serial # which is stored in ROM

0x08 - 0x0A

Always 0

0x0B

LocalID

0x0C

wdoglj (Watchdog Variable)

0x0D

wdogtoh (Watchdog Variable)

0x0E

wdogtol (Watchdog Variable)

0x070

fullA (Asynch Variable)

0x071

fullB (Asynch Variable)

0x072

fullC (Asynch Variable)

0x073

halfA (Asynch Variable)

0x074

halfB (Asynch Variable)

0x075

halfC (Asynch Variable)

0x076

tomult (Asynch Variable)

0x080 - 0x0BF

Serial data send buffer (64 bytes, 28 used)

0x0C0 - 0x0FF

Serial data receive buffer (64 bytes, 28 used)

0x1C0 - 0x1DF

Serial data buffer (32 bytes)

0x200 - 0x3FF

User area

0x400 - 0x1FFF

Circular RAM buffer.

LabJackPython Example

>>> import u12
>>> d = u12.U12(debug=True)
open called
Writing: [0x0, 0x0, 0x0, 0x0, 0x0, 0x57, 0x0, 0x0]
Received: [0x57, 0x0, 0x0, 0x0, 0xff, 0xff, 0x0, 0x0]
>>> r = d.rawReadRAM()
Writing: [0x0, 0x0, 0x0, 0x0, 0x0, 0x50, 0x0, 0x0]
Received: [0x50, 0x5, 0xf6, 0x8b, 0xaa, 0x0, 0x0, 0x0]
>>> print r
{'DataByte3': 5, 'DataByte2': 246, 'DataByte1': 139, 'DataByte0': 170}
>>> bytes = [ r['DataByte3'], r['DataByte2'], r['DataByte1'], r['DataByte0'] ]
>>> import struct
>>> print struct.unpack(">I", struct.pack("BBBB", *bytes))[0]
100043690

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