Support for User Defined Types (UDT)

[nusaqib]

I know it's a long shot but it would be great to have support for UDTs at least only for reading PVs as in most machine/equipment protection systems there is a small set of writable PVs as compared to readable ones. The idea is to just specify controller tag and if it is a UDT, subsequent members are converted to separate EPICS PVs automatically by:

• Automatic mapping of PLC tag data types to EPICS record types (e.g. BOOL to bi, REAL to ai etc.)
• Dot notation of PLC could be converted to any convention (e.g. colon ":") in EPICS PV name

[kasemir]

I'm totally fine with you implementing this.
Use the command line test tool at full verbosity to read some supported tag type like a DINT:

ether_ip_test -i IP.OF.YOUR.PLC -v 10 Some_DINT_Tag

In the output, you'll find this:

MR_Response:
    USINT service         = 0xCC (Response to CIP_ReadData)
    USINT reserved        = 0x00
    USINT status          = 0x00 (Ok)
    USINT ext. stat. size = 0
    Data (net format) =
    00000000 C4 00 00 00 00 00                               - ......
    Data =  DINT 0

Now try that with

ether_ip_test -i IP.OF.YOUR.PLC -v 10 Some_User_Defined_Tag

What does the response from the PLC look like?
Back when I implemented this based on the information in 1756-RM005A-EN-E.pdf, "Logix5000 Data Access", the documentation didn't make it obvious to me what a user defined structure would look like and how to decode it.

[nusaqib]

Hi Kay, the output for the "Circ1" UDT in the following screenshot is as follows:

nusaqib@nusaqib-Virtual-Machine:~/epics/ubuntu-22.04/7.0.7/modules/ether_ip/bin/linux-x86_64$ ./ether_ip_test -i 128.3.131.203 -v 10 Circ1
Tag 'Circ1'
EIP connectWithTimeout(128.3.131.203:44818, 5 sec, 0 msec)
EIP connected to 128.3.131.203:44818 on socket 3
EIP sending ListServices encapsulation command
EncapsulationHeader:
    UINT  command   = 0x04 (ListServices)
    UINT  length    = 0 
    UDINT session   = 0x00000000
    UDINT status    = 0x00000000 (OK)
    USINT context[8]= '00000001'
    UDINT options   = 0x00000000
Data sent (24 bytes):
00000000 04 00 00 00 00 00 00 00 00 00 00 00 30 30 30 30 - ............0000
00000010 30 30 30 31 00 00 00 00                         - 0001....
Data Received (50 bytes):
00000000 04 00 1A 00 00 00 00 00 00 00 00 00 30 30 30 30 - ............0000
00000010 30 30 30 31 00 00 00 00 01 00 00 01 14 00 01 00 - 0001............
00000020 20 01 43 6F 6D 6D 75 6E 69 63 61 74 69 6F 6E 73 -  .Communications
00000030 00 00                                           - ..
EncapsulationHeader:
    UINT  command   = 0x04 (ListServices)
    UINT  length    = 26 
    UDINT session   = 0x00000000
    UDINT status    = 0x00000000  (OK)
    USINT context[8]= '00000001'
    UDINT options   = 0x00000000
ListServices reply
    UINT count     = 1
    UINT type     = 0x0100
    UINT length   = 20
    UINT version  = 0x0001
    UINT flags    = 0x0120 (CIP PDU encap.)
    USINT name[16]= 'Communications'
EIP sending RegisterSession encapsulation command
EncapsulationHeader:
    UINT  command   = 0x65 (RegisterSession)
    UINT  length    = 4 
    UDINT session   = 0x00000000
    UDINT status    = 0x00000000 (OK)
    USINT context[8]= '00000002'
    UDINT options   = 0x00000000
    UINT  protocol  = 1 
    UINT  options   = 0 
Data sent (28 bytes):
00000000 65 00 04 00 00 00 00 00 00 00 00 00 30 30 30 30 - e...........0000
00000010 30 30 30 32 00 00 00 00 01 00 00 00             - 0002........
Data Received (28 bytes):
00000000 65 00 04 00 0F 02 00 40 00 00 00 00 30 30 30 30 - e......@....0000
00000010 30 30 30 32 00 00 00 00 01 00 00 00             - 0002........
EncapsulationHeader:
    UINT  command   = 0x65 (RegisterSession)
    UINT  length    = 4 
    UDINT session   = 0x4000020F
    UDINT status    = 0x00000000  (OK)
    USINT context[8]= '00000002'
    UDINT options   = 0x00000000
EIP Reading attribute
EncapsulationHeader:
    UINT  command   = 0x6F (SendRRData)
    UINT  length    = 24 
    UDINT session   = 0x4000020F
    UDINT status    = 0x00000000 (OK)
    USINT context[8]= '00000003'
    UDINT options   = 0x00000000
Send RR Data
    UDINT interface handle   0
    UINT timeout             0
    UINT count (addr., data) 2
    UINT address_type        0x00 (UCMM)
    UINT address_length      0
    UINT data_type           0xB2 (Unconnected Message)
    UINT data_length         8
MR Request
    USINT service   = 0xE (Get_Attribute_Single)
    USINT path size = 3 words
    Path: Class(0x20) 0x1 (Identity), instance(0x24) 1, attrib.(0x30) 0x1
Data sent (48 bytes):
00000000 6F 00 18 00 0F 02 00 40 00 00 00 00 30 30 30 30 - o......@....0000
00000010 30 30 30 33 00 00 00 00 00 00 00 00 00 00 02 00 - 0003............
00000020 00 00 00 00 B2 00 08 00 0E 03 20 01 24 01 30 01 - .......... .$.0.
Data Received (46 bytes):
00000000 6F 00 16 00 0F 02 00 40 00 00 00 00 30 30 30 30 - o......@....0000
00000010 30 30 30 33 00 00 00 00 00 00 00 00 00 00 02 00 - 0003............
00000020 00 00 00 00 B2 00 06 00 8E 00 00 00 01 00       - ..............
EncapsulationHeader:
    UINT  command   = 0x6F (SendRRData)
    UINT  length    = 22 
    UDINT session   = 0x4000020F
    UDINT status    = 0x00000000  (OK)
    USINT context[8]= '00000003'
    UDINT options   = 0x00000000
Received RR Data
    UDINT interface handle  0
    UINT timeout            0
    UINT count (addr+data)  2
    UINT address_type       0x0 (UCMM)
    UINT address_length     0
    UINT data_type          0xB2 (Unconnected Message)
    UINT data_length        6
MR_Response:
    USINT service         = 0x8E (Response to Get_Attribute_Single)
    USINT reserved        = 0x00
    USINT status          = 0x00 (Ok)
    USINT ext. stat. size = 0
    Data (net format) =
    00000000 01 00                                           - ..
EIP Reading attribute
EncapsulationHeader:
    UINT  command   = 0x6F (SendRRData)
    UINT  length    = 24 
    UDINT session   = 0x4000020F
    UDINT status    = 0x00000000 (OK)
    USINT context[8]= '00000004'
    UDINT options   = 0x00000000
Send RR Data
    UDINT interface handle   0
    UINT timeout             0
    UINT count (addr., data) 2
    UINT address_type        0x00 (UCMM)
    UINT address_length      0
    UINT data_type           0xB2 (Unconnected Message)
    UINT data_length         8
MR Request
    USINT service   = 0xE (Get_Attribute_Single)
    USINT path size = 3 words
    Path: Class(0x20) 0x1 (Identity), instance(0x24) 1, attrib.(0x30) 0x2
Data sent (48 bytes):
00000000 6F 00 18 00 0F 02 00 40 00 00 00 00 30 30 30 30 - o......@....0000
00000010 30 30 30 34 00 00 00 00 00 00 00 00 00 00 02 00 - 0004............
00000020 00 00 00 00 B2 00 08 00 0E 03 20 01 24 01 30 02 - .......... .$.0.
Data Received (46 bytes):
00000000 6F 00 16 00 0F 02 00 40 00 00 00 00 30 30 30 30 - o......@....0000
00000010 30 30 30 34 00 00 00 00 00 00 00 00 00 00 02 00 - 0004............
00000020 00 00 00 00 B2 00 06 00 8E 00 00 00 0E 00       - ..............
EncapsulationHeader:
    UINT  command   = 0x6F (SendRRData)
    UINT  length    = 22 
    UDINT session   = 0x4000020F
    UDINT status    = 0x00000000  (OK)
    USINT context[8]= '00000004'
    UDINT options   = 0x00000000
Received RR Data
    UDINT interface handle  0
    UINT timeout            0
    UINT count (addr+data)  2
    UINT address_type       0x0 (UCMM)
    UINT address_length     0
    UINT data_type          0xB2 (Unconnected Message)
    UINT data_length        6
MR_Response:
    USINT service         = 0x8E (Response to Get_Attribute_Single)
    USINT reserved        = 0x00
    USINT status          = 0x00 (Ok)
    USINT ext. stat. size = 0
    Data (net format) =
    00000000 0E 00                                           - ..
EIP Reading attribute
EncapsulationHeader:
    UINT  command   = 0x6F (SendRRData)
    UINT  length    = 24 
    UDINT session   = 0x4000020F
    UDINT status    = 0x00000000 (OK)
    USINT context[8]= '00000005'
    UDINT options   = 0x00000000
Send RR Data
    UDINT interface handle   0
    UINT timeout             0
    UINT count (addr., data) 2
    UINT address_type        0x00 (UCMM)
    UINT address_length      0
    UINT data_type           0xB2 (Unconnected Message)
    UINT data_length         8
MR Request
    USINT service   = 0xE (Get_Attribute_Single)
    USINT path size = 3 words
    Path: Class(0x20) 0x1 (Identity), instance(0x24) 1, attrib.(0x30) 0x4
Data sent (48 bytes):
00000000 6F 00 18 00 0F 02 00 40 00 00 00 00 30 30 30 30 - o......@....0000
00000010 30 30 30 35 00 00 00 00 00 00 00 00 00 00 02 00 - 0005............
00000020 00 00 00 00 B2 00 08 00 0E 03 20 01 24 01 30 04 - .......... .$.0.
Data Received (46 bytes):
00000000 6F 00 16 00 0F 02 00 40 00 00 00 00 30 30 30 30 - o......@....0000
00000010 30 30 30 35 00 00 00 00 00 00 00 00 00 00 02 00 - 0005............
00000020 00 00 00 00 B2 00 06 00 8E 00 00 00 22 0B       - ............".
EncapsulationHeader:
    UINT  command   = 0x6F (SendRRData)
    UINT  length    = 22 
    UDINT session   = 0x4000020F
    UDINT status    = 0x00000000  (OK)
    USINT context[8]= '00000005'
    UDINT options   = 0x00000000
Received RR Data
    UDINT interface handle  0
    UINT timeout            0
    UINT count (addr+data)  2
    UINT address_type       0x0 (UCMM)
    UINT address_length     0
    UINT data_type          0xB2 (Unconnected Message)
    UINT data_length        6
MR_Response:
    USINT service         = 0x8E (Response to Get_Attribute_Single)
    USINT reserved        = 0x00
    USINT status          = 0x00 (Ok)
    USINT ext. stat. size = 0
    Data (net format) =
    00000000 22 0B                                           - ".
EIP Reading attribute
EncapsulationHeader:
    UINT  command   = 0x6F (SendRRData)
    UINT  length    = 24 
    UDINT session   = 0x4000020F
    UDINT status    = 0x00000000 (OK)
    USINT context[8]= '00000006'
    UDINT options   = 0x00000000
Send RR Data
    UDINT interface handle   0
    UINT timeout             0
    UINT count (addr., data) 2
    UINT address_type        0x00 (UCMM)
    UINT address_length      0
    UINT data_type           0xB2 (Unconnected Message)
    UINT data_length         8
MR Request
    USINT service   = 0xE (Get_Attribute_Single)
    USINT path size = 3 words
    Path: Class(0x20) 0x1 (Identity), instance(0x24) 1, attrib.(0x30) 0x6
Data sent (48 bytes):
00000000 6F 00 18 00 0F 02 00 40 00 00 00 00 30 30 30 30 - o......@....0000
00000010 30 30 30 36 00 00 00 00 00 00 00 00 00 00 02 00 - 0006............
00000020 00 00 00 00 B2 00 08 00 0E 03 20 01 24 01 30 06 - .......... .$.0.
Data Received (48 bytes):
00000000 6F 00 18 00 0F 02 00 40 00 00 00 00 30 30 30 30 - o......@....0000
00000010 30 30 30 36 00 00 00 00 00 00 00 00 00 00 02 00 - 0006............
00000020 00 00 00 00 B2 00 08 00 8E 00 00 00 74 2B 51 D0 - ............t+Q.
EncapsulationHeader:
    UINT  command   = 0x6F (SendRRData)
    UINT  length    = 24 
    UDINT session   = 0x4000020F
    UDINT status    = 0x00000000  (OK)
    USINT context[8]= '00000006'
    UDINT options   = 0x00000000
Received RR Data
    UDINT interface handle  0
    UINT timeout            0
    UINT count (addr+data)  2
    UINT address_type       0x0 (UCMM)
    UINT address_length     0
    UINT data_type          0xB2 (Unconnected Message)
    UINT data_length        8
MR_Response:
    USINT service         = 0x8E (Response to Get_Attribute_Single)
    USINT reserved        = 0x00
    USINT status          = 0x00 (Ok)
    USINT ext. stat. size = 0
    Data (net format) =
    00000000 74 2B 51 D0                                     - t+Q.
EIP Reading attribute
EncapsulationHeader:
    UINT  command   = 0x6F (SendRRData)
    UINT  length    = 24 
    UDINT session   = 0x4000020F
    UDINT status    = 0x00000000 (OK)
    USINT context[8]= '00000007'
    UDINT options   = 0x00000000
Send RR Data
    UDINT interface handle   0
    UINT timeout             0
    UINT count (addr., data) 2
    UINT address_type        0x00 (UCMM)
    UINT address_length      0
    UINT data_type           0xB2 (Unconnected Message)
    UINT data_length         8
MR Request
    USINT service   = 0xE (Get_Attribute_Single)
    USINT path size = 3 words
    Path: Class(0x20) 0x1 (Identity), instance(0x24) 1, attrib.(0x30) 0x7
Data sent (48 bytes):
00000000 6F 00 18 00 0F 02 00 40 00 00 00 00 30 30 30 30 - o......@....0000
00000010 30 30 30 37 00 00 00 00 00 00 00 00 00 00 02 00 - 0007............
00000020 00 00 00 00 B2 00 08 00 0E 03 20 01 24 01 30 07 - .......... .$.0.
Data Received (58 bytes):
00000000 6F 00 22 00 0F 02 00 40 00 00 00 00 30 30 30 30 - o."....@....0000
00000010 30 30 30 37 00 00 00 00 00 00 00 00 00 00 02 00 - 0007............
00000020 00 00 00 00 B2 00 12 00 8E 00 00 00 0D 35 30 36 - .............506
00000030 39 2D 4C 33 32 30 45 52 2F 41                   - 9-L320ER/A
EncapsulationHeader:
    UINT  command   = 0x6F (SendRRData)
    UINT  length    = 34 
    UDINT session   = 0x4000020F
    UDINT status    = 0x00000000  (OK)
    USINT context[8]= '00000007'
    UDINT options   = 0x00000000
Received RR Data
    UDINT interface handle  0
    UINT timeout            0
    UINT count (addr+data)  2
    UINT address_type       0x0 (UCMM)
    UINT address_length     0
    UINT data_type          0xB2 (Unconnected Message)
    UINT data_length        18
MR_Response:
    USINT service         = 0x8E (Response to Get_Attribute_Single)
    USINT reserved        = 0x00
    USINT status          = 0x00 (Ok)
    USINT ext. stat. size = 0
    Data (net format) =
    00000000 0D 35 30 36 39 2D 4C 33 32 30 45 52 2F 41       - .5069-L320ER/A
------------------------------
Identity information of target:
    UINT vendor         = 0x0001
    UINT device_type    = 0x000E
    UINT revision       = 0x0B22
    UDINT serial_number = 0xD0512B74
    USINT name          = '5069-L320ER/A'
------------------------------
EIP read tag
EncapsulationHeader:
    UINT  command   = 0x6F (SendRRData)
    UINT  length    = 42 
    UDINT session   = 0x4000020F
    UDINT status    = 0x00000000 (OK)
    USINT context[8]= '00000008'
    UDINT options   = 0x00000000
Send RR Data
    UDINT interface handle   0
    UINT timeout             0
    UINT count (addr., data) 2
    UINT address_type        0x00 (UCMM)
    UINT address_length      0
    UINT data_type           0xB2 (Unconnected Message)
    UINT data_length         26
MR Request
    USINT service   = 0x52 (CM_Unconnected_Send)
    USINT path size = 2 words
    Path: Class(0x20) 0x6 (ConnectionManager), instance(0x24) 1
    USINT tick time   = 10
    USINT ticks       = 240
    UINT message size = 12 (0x000C)
    ... (embedded message of 12 bytes)
    USINT path_size   = 1 words
    USINT reserved    = 0x0
    Path: Port 1, link 0
Embedded Message:
MR Request
    USINT service   = 0x4C (CIP_ReadData)
    USINT path size = 4 words
    Path: Tag 'Circ1'
    UINT elements = 1
Data sent (66 bytes):
00000000 6F 00 2A 00 0F 02 00 40 00 00 00 00 30 30 30 30 - o.*....@....0000
00000010 30 30 30 38 00 00 00 00 00 00 00 00 00 00 02 00 - 0008............
00000020 00 00 00 00 B2 00 1A 00 52 02 20 06 24 01 0A F0 - ........R. .$...
00000030 0C 00 4C 04 91 05 43 69 72 63 31 00 01 00 01 00 - ..L...Circ1.....
00000040 01 00                                           - ..
Data Received (184 bytes):
00000000 6F 00 A0 00 0F 02 00 40 00 00 00 00 30 30 30 30 - o......@....0000
00000010 30 30 30 38 00 00 00 00 00 00 00 00 00 00 02 00 - 0008............
00000020 00 00 00 00 B2 00 90 00 CC 00 00 00 A0 02 C0 7D - ...............}
00000030 00 00 40 40 00 00 00 40 00 00 80 3F 1F 00 00 00 - ..@@...@...?....
00000040 00 00 80 3F 00 00 00 40 00 00 40 40 1F 00 00 00 - ...?...@..@@....
00000050 00 00 80 3F 00 00 00 40 00 00 40 40 1F 00 00 00 - ...?...@..@@....
00000060 00 00 80 3F 00 00 00 40 00 00 40 40 17 00 00 00 - ...?...@..@@....
00000070 00 00 40 40 00 00 00 40 00 00 80 3F 17 00 00 00 - ..@@...@...?....
00000080 00 00 80 3F 00 00 00 40 00 00 40 40 17 00 00 00 - ...?...@..@@....
00000090 00 00 00 00 0B 00 00 00 01 00 00 00 0B 00 00 00 - ................
000000A0 0B 00 00 00 01 00 00 00 0B 00 00 00 0B 00 00 00 - ................
000000B0 01 00 00 00 0B 00 00 00                         - ........
EncapsulationHeader:
    UINT  command   = 0x6F (SendRRData)
    UINT  length    = 160 
    UDINT session   = 0x4000020F
    UDINT status    = 0x00000000  (OK)
    USINT context[8]= '00000008'
    UDINT options   = 0x00000000
Received RR Data
    UDINT interface handle  0
    UINT timeout            0
    UINT count (addr+data)  2
    UINT address_type       0x0 (UCMM)
    UINT address_length     0
    UINT data_type          0xB2 (Unconnected Message)
    UINT data_length        144
MR_Response:
    USINT service         = 0xCC (Response to CIP_ReadData)
    USINT reserved        = 0x00
    USINT status          = 0x00 (Ok)
    USINT ext. stat. size = 0
    Data (net format) =
    00000000 A0 02 C0 7D 00 00 40 40 00 00 00 40 00 00 80 3F - ...}..@@...@...?
00000010 1F 00 00 00 00 00 80 3F 00 00 00 40 00 00 40 40 - .......?...@..@@
00000020 1F 00 00 00 00 00 80 3F 00 00 00 40 00 00 40 40 - .......?...@..@@
00000030 1F 00 00 00 00 00 80 3F 00 00 00 40 00 00 40 40 - .......?...@..@@
00000040 17 00 00 00 00 00 40 40 00 00 00 40 00 00 80 3F - ......@@...@...?
00000050 17 00 00 00 00 00 80 3F 00 00 00 40 00 00 40 40 - .......?...@..@@
00000060 17 00 00 00 00 00 00 00 0B 00 00 00 01 00 00 00 - ................
00000070 0B 00 00 00 0B 00 00 00 01 00 00 00 0B 00 00 00 - ................
00000080 0B 00 00 00 01 00 00 00 0B 00 00 00             - ............
    Data =  Unknown CIP struct (type 0x02A0) 0x7DC0: 
Unknown CIP struct (type 0x02A0) 0x7DC0: 
EIP sending UnRegisterSession encapsulation command, session ID 0x4000020F
EncapsulationHeader:
    UINT  command   = 0x66 (UnRegisterSession)
    UINT  length    = 0 
    UDINT session   = 0x4000020F
    UDINT status    = 0x00000000 (OK)
    USINT context[8]= '00000009'
    UDINT options   = 0x00000000
Data sent (24 bytes):
00000000 66 00 00 00 0F 02 00 40 00 00 00 00 30 30 30 30 - f......@....0000
00000010 30 30 30 39 00 00 00 00                         - 0009....
EIP disconnecting socket 3
nusaqib@nusaqib-Virtual-Machine:~/epics/ubuntu-22.04/7.0.7/modules/ether_ip/bin/linux-x86_64$ 

[nusaqib]

I would be glad to do this but I lack expertise. It would be my first real coding project, could you guide me the path/flow so that I can see if I'll be able to do it?

[kasemir]

After the initial connection establishment and readout of vendor code, serial number etc., we read that Tag 'Circ1' and as a data reply we get this:

MR_Response:
    USINT service         = 0xCC (Response to CIP_ReadData)
    USINT reserved        = 0x00
    USINT status          = 0x00 (Ok)
    USINT ext. stat. size = 0
    Data (net format) =
    00000000 A0 02 C0 7D 00 00 40 40 00 00 00 40 00 00 80 3F - ...}..@@...@...?
00000010 1F 00 00 00 00 00 80 3F 00 00 00 40 00 00 40 40 - .......?...@..@@
00000020 1F 00 00 00 00 00 80 3F 00 00 00 40 00 00 40 40 - .......?...@..@@
00000030 1F 00 00 00 00 00 80 3F 00 00 00 40 00 00 40 40 - .......?...@..@@
00000040 17 00 00 00 00 00 40 40 00 00 00 40 00 00 80 3F - ......@@...@...?
00000050 17 00 00 00 00 00 80 3F 00 00 00 40 00 00 40 40 - .......?...@..@@
00000060 17 00 00 00 00 00 00 00 0B 00 00 00 01 00 00 00 - ................
00000070 0B 00 00 00 0B 00 00 00 01 00 00 00 0B 00 00 00 - ................
00000080 0B 00 00 00 01 00 00 00 0B 00 00 00             - ............
    Data =  Unknown CIP struct (type 0x02A0) 0x7DC0

Compare with a plain DINT where we get

00000000 C4 00 00 00 00 00                               - ......

In that reply, 0xC4 00 describes the data type as DINT, followed by 4 bytes for that actual value, in this case zero.

For the custom data type, we get type 0x02A0 0x7DC0, meaning "custom structure of template type 0x7DC0".
Begs the question what template type 0x7DC0 looks like. What are the element names and data types?

It's possible that the "Read Template" service code 0x4C 03 .. can be used for that, but the info I have on that is too little to go by.