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