Unprotected Read in Micrologix 1200

Hello All,

I wrote a code to execute the unprotected read for DF1. I created two Long (32 bits)data files numbered 9 and 10 where file 9 (L9) and file 10(L10) each with 200 elements. The problem is I could not read element in file L10. Any body have an idea what I am doing wrong?

The syntax I am using is
[DLE STX][DST][SRC][CMD][STS][TNS1][TNS2][ADDL][ADDH][SIZE][DLE ETX][CRC]
An instance of this syntax is (Numbers are in decimal):
[DLE STX][1 ][0 ][1 ][0 ][46 ][3 ][36 ][3 ][200 ][DLE ETX][CRC]
I calculated [ADDL][ADDH] as [36 ][3 ] to correspond to byte 804 which I beleive it should be the first element in L10 ( L9 have 200 elements. Accordingly, I used 201 * 4).
I am getting all the acknolowdgement from ML1200 but the data I am getting isdifferent from what is in L10.
thanks for your help in advance
Thanks in advance.
Best to all

If you want to post your code, it would probably make it a little easier to figure out what's going on. If not, just let us know the details of how your message is set up now, and we'll try to lead you in the right direction.

I altered my posted question to reflect better how I am doing it.
I noticed that I can read only file 9 with the unprotected read command. What I should do to read file 10?

Data File 9 in Allen-Bradley controllers has a special meaning to the communication port; it functions as the "Common Interface File" (CIF) which means that it can reply to the oldest, most primitive DF1 command, which is the one you are using.

"Unprotected File Read" is supported by all A-B controllers so that they can exchange messages with the very oldest PLC-2 controllers.

But this command is limited to reading the Common Interface File, which is by default File 9.

In addition, A-B data files should not generally be thought of as contigous physical memory; you can't send a request to read past the end of File 9 and get data from the beginning of File 10.

If you want to get data from a MicroLogix 1500 controller, you should implement DF1 command codes for "Protected Typed Logical Read". Here's a hint: "L" files are file type 0x91.

Thanks a lot Ken Roach. I could not find any where that type L code is 91 hex. I lost about three days trying on the protected read, but it worked only after learning from you that type L code is 91.

Thanks a lot