PLC, PACSystems & Industrial Computing Forum - Recent Threads

RE: Questions about 90-30 in process of upgrading

Steve Ward — Tue, 03 Sep 2024 08:36:11 GMT

Hi Matthew!

Emerson can only provide limited guidance for programming and in practice there are as many options for controlling a machine as there are developers! Here is some advice.

There is always some risk when working live on a PLC, especially as this Series 90-30 CPU331 is so old. I recommend modernising to PACSystems RX3i which is supported and offers better fault finding and monitoring options. PACSystems RX3i also stores documentation in the PLC so you won't lose this in future.

Note that very old PLC programs were constrained by memory and speed. So developers used a variety of "tricks" to minimise the amount of logic and enhance performance, usually at the expense of readability. Some old PLC programs were translated from even earlier applications using Instruction List and this can introduce program structures that make little sense in ladder logic. Also today PLC programming is somewhat standardised under IEC 61131-3 and by organisations like PLCOpen but this was not the case in the past.

The BIT_SEQ instruction is commonly used for providing a sequence, converting a sequence number into a bit that can be used by standard ladder instructions. So yes this reduces the amount of programming required, compared to say using a counter and EQ type instructions, although EQ might be more readable by humans. BIT_SEQ performs a bit sequence shift through a series of contiguous bits (bits) starting at ST and sets the bit pointed to by the sequence number. The bit set moves by direction DIR and amount N whenever the OK input comes on (false to true transition). BIT_SEQ needs instance data like a timer or counter so this is what the R00013 value is. R is reset. See the CPU Programmer’s Reference Manual, GFK-2950, or PAC Machine Edition Help, for more details.

PAC Machine Edition is strongly typed, but you can override type mismatch issues in the options tab of the project's properties. The developer has to keep track of what the data means and how it is used in the application.

I don't see why you would OR a value with itself, this is effectively always passing power to the next set of instructions. Possibilities are that the developer wanted to be able to see the status of the bit at all times, or they modified the logic at a later stage but didn't want to completely remove the possibility of changing back at a later date, or some other reason lost in the mists of time.

%Q is intended for physical outputs but many developers use spare %Q as %M.

ONDTR accumulates time. The stopwatch timer did exist at the launch of the Series 90-30 but maybe the developer wasn't aware of this or they were used to doing it another way.

PAC Machine Edition can be used for live monitoring of the data tables and the ladder logic. For ladder logic, the programmer and PLC must be LOGIC EQUAL. You can always force LOGIC EQUAL by uploading from the PLC, but you may lose any documentation when doing this. Some very old CPUs are not compatible with PAC Machine Edition, for CPU331 you must have at least firmware version 8.21 or later. Older CPU331 cannot be updated as they are no longer supported (the firmware is in EPROM and needs a physical chip).

Questions about 90-30 in process of upgrading

Matthew Love — Thu, 29 Aug 2024 17:33:09 GMT

Hello,

I have the task of updating an old PLC in a plant. I have a copy of the old program, but it is absent of any names and comments. Given that the cabinet is nearly 35 years old, documentation is also scarce.

It is a somewhat simple LD program with 150 rungs. I do know what the hard-wire I/O are (thanks for wire labels!), so I have filled in those names for %I and %Q variables respectively, then using those knowns to back-fill unknown memory variables.

The existing machine is a 90-30, model 331.

In trying to decipher the old program, a few things I cannot quite wrap my head around.

The biggest head-scratcher for me (likely because I lack old school experience) is the use of BIT_SEQ. I've read the description several times, but the concept (or perhaps the implementation here) doesn't click for me.
- I understand the enable, reset, and direction, but the N and ST parameters escape me a bit, or at least the ones used here. N is a constant, and a large number at 393. The description says that N is "the value that the step number is set to when R is energized" and that N must be between 1 and Length, while Length's legal values are 1-256. Given this, 393 is input very specifically, but it would just default to 256 (max Length) or the Length value of 5 here, unless I'm missing something.
  - I believe the 393 is specifically linked to the start of a cluster of 5 (Length's parameter) BOOLs in %M, from 393-397, which are then linked to %Q outputs.
  - Following this, it seems that they used the BIT_SEQ to turn on the Qs via a crank-style bit manipulation vs traditional LD rung logic.
- Second, the ST argument. When compiling the program, PAC ME gives warnings on all BIT_SEQ (4 of them) in the program, citing a type mismatch on the ST arguments, as they are all provided as BOOL, but expecting BYTE, WORD, or DWORD.
  - I'm assuming that BYTE, WORD, or DWORDs are just suggestions, and really all that matters is the numerical address provided, in this case marked by SV1_V variable, which is address %M00393 - matching the N argument.

Are my assumptions correct here? It looks like they gave the BIT_SEQ the starting address of 393, which is also the address of the ST argument. The BIT_SEQ cranks through the bits to turn on 5 BOOLs. I can understand the effective/technical result here, but I'm not sure why you would choose this method to activate coils rather than traditional rung logic? Perhaps to minimize number of rungs/instructions for sake of memory limitations?

Another question:
Several times throughout the program, a variable will be OR'd with NOT-itself. Like (if VAR1 == TRUE OR VAR1 != TRUE) THEN ....
Again, given that this, at first glance, seems obtuse, I have to assume this might be some facet/restriction of programming in times long ago that I'm not familiar with. My best guess is adding this chunk in as a sort of marker for human visualization purposes, in lieu of a comment.

Another peculiar thing I've found is the use of %Qs in addresses far above where the hard-wired inputs stop.
For example, this application's I/O cards stop at %Q00036, but there exists %Q00203, 204, and 210 in the program. I assume these are used in place of %M, but why? I do not believe %M memory was exhausted... I understand these may simply be idiosyncrasies of a rouge programmer, but curious of there might be some reason (from before I was born!) giving legitimate cause for this.

One more question: this program has pervasive use of ONDTR TENTHS instruction. I understand the purpose of a delay-on-make function, of course, but the kicker is that ONDTR (as I read it) has a cumulative timer, so that it does not reset to the specified parameter when power flow is broken - it holds its value.
I can understand the utility of this in certain applications, but I'm surprised at the exclusive use of this instruction for all timer functions in the program. A few times, the input trigger is inverted, causing it to auto-reset upon power break, or the output will be wrapped around to the Reset.
Given its exclusive use and occasional go-arounds, I can only assume that a plain delay-on-make might not have existed in this era?

Lastly, can I connect to this PLC live via PAC ME? There is some doubt with my colleagues that PAC ME cannot be connected to a 90-30 of fear that it will 'update' something in the PLC, causing it to no longer work with the old software (MS-DOS style stuff). Is there any validity this? To clarify, we (technicians) have PAC ME, the customer only has old software (LogicMaster? I believe?) so do not want to leave site causing unknown problems for customer.

Thanks for the help and tolerance of my many questions.

QuickPanel Plus History Alarms to CSV

Gabriele Corrieri — Tue, 13 Aug 2024 14:03:08 GMT

Hello

I'm very newbie to Emerson products, I need a way (script?) to write on USB memory a CSV of all historical alarms:

I've not found any resource, on manuals, on web (also here) that explain how to do this (I think) relative simple task.

RE: QuickPanel Plus History Alarms to CSV

Gabriele Corrieri — Tue, 27 Aug 2024 15:29:30 GMT

Hello Mats I'm again hands on (I've some trouble in the past week with higher priority to solve)

I've open just few hours ago the online help, but since I've newbie both in general HMI scripting and Emerson products, what I've found is that:

the 3rd row is the core of function explain and is very short

I'm very confused because my target is making a new page with a button, and maybe the destination directory and filename with the contents of the historical alarm table

Because the CSV on output will be read by human technician unuseful or redundant columns are not a problem.

I hope that explanation is more detailed from the past.

Thanks in advance for any help

RE: QuickPanel Plus History Alarms to CSV

Mats Andersson — Thu, 15 Aug 2024 16:38:45 GMT

Yes, we could probably do a better job with the user docs. The ViewLogToHistorianCSV is described in the PAC Machine Edition help file. The function is intended to be used with the Proficy Historian product from GE, but it's just a CSV text file. Ignore all the GE Proficy Historian references. As I mentioned this function will have a number of columns you don't need/want so it may not work for your application.

RE: QuickPanel Plus History Alarms to CSV

Gabriele Corrieri — Wed, 14 Aug 2024 22:38:35 GMT

Hello Mats: what you mean when youi type "there is also a script function named" I've not founf any for that keyword.
to be truly honest I've found I've found that two pages
www.ge.com/.../t_hgs_managing_log_files.html
www.ge.com/.../c_hgs_about_historian_log_files.html
that explain something about an external tool for logging: my target is a hmi pushbutton that catch all the history alarm box and write as-is to an CSV file keeping all event date and time: in case of trouble technician on-site will put an usb memory key into panel, push the button and wait for csv writing, than extract the key and on a desktop or laptop computer send that file to me for troubleshooting

Thanks again

RE: QuickPanel Plus History Alarms to CSV

Gabriele Corrieri — Wed, 14 Aug 2024 22:25:18 GMT

Very thanks again Steve!!

RE: QuickPanel Plus History Alarms to CSV

Mats Andersson — Wed, 14 Aug 2024 14:42:09 GMT

Gabriele, there is also a script function named "ViewLogToHistorianCSV". This will generate a CSV file with data from the panels historical logging function. It probably generates a number of columns you don't care about but is an easy way to get there.

RE: QuickPanel Plus History Alarms to CSV

Steve Ward — Wed, 14 Aug 2024 08:56:02 GMT

PAC Machine Edition help has a section on QuickPanel+ scripting and a ViewScript script reference. For VBscript, PAC Machine Editionhas an overview and additional resources are available online. See also the QuickPanel+ documents on our Emerson Customer Centre at emerson-mas.my.site.com/communities - search for QuickPanel+ or start at the QuickPanel+ landing page: emerson-mas.my.site.com/.../QuickPanel-Plus-Landing-Page.

RE: QuickPanel Plus History Alarms to CSV

Gabriele Corrieri — Wed, 14 Aug 2024 08:03:04 GMT

Very very very thanks Steve: I'll check, adapt and test the code from next week, when I put the hand again: my first problem is reach (both in ViewScript and VBScript) the correct data in QP+ the keyword and other specific things related to this customized version of scripting.
Without abuse your patience could you link the manuals that explain scripting in QP+? I've download some ot that but none have deep explanations of scripting languages.

Thank you again Steve

RE: QuickPanel Plus History Alarms to CSV

Gabriele Corrieri — Wed, 14 Aug 2024 07:54:10 GMT

Hello Andre, thank you for quck answer: my target is Emerson RX3i CPE305 so all related to powerful DeltaV DCS are not applicable here.

RE: QuickPanel Plus History Alarms to CSV

Steve Ward — Tue, 13 Aug 2024 16:00:49 GMT

If you have QuickPanel+ operator interface, this is easily achievable using a script. The QuickPanel+ supports both proprietary ViewScript as well as open VBScript. ViewScript is better documented in PAC Machine Edition but VBScript should give more flexibility and run faster.

Here is a sample VBScript:

'-------------------------------------
' Script Created: Feb 20, 2018
' Description: Log Data To CSV File
' Application script period = 60000 ms = 1 minute
' VBScript
'-------------------------------------
'Get current year, make as start of file name
LOGFILENAME.Value = Cstr(CurrentTime.Element("YR").Value)
'Get current month, add to file name
LOGCURRENTMONTH.Value = CurrentTime.Element("MO").Value
If LOGCURRENTMONTH.Value < 10 Then
LOGFILENAME.Value = LOGFILENAME.Value + "0"
End If
LOGFILENAME.Value = LOGFILENAME.Value + Cstr(LOGCURRENTMONTH.Value)
'Get current day, add to file name
LOGCURRENTDAY.Value = CurrentTime.Element("DAY").Value
If LOGCURRENTDAY.Value < 10 Then
LOGFILENAME.Value = LOGFILENAME.Value + "0"
End If
LOGFILENAME.Value = LOGFILENAME.Value + Cstr(LOGCURRENTDAY.Value)
'Get current hour, add to file name
LOGCURRENTHOUR.Value = CurrentTime.Element("HR").Value
If LOGCURRENTHOUR.Value < 10 Then
LOGFILENAME.Value = LOGFILENAME.Value + "0"
End If
LOGFILENAME.Value = LOGFILENAME.Value + Cstr(LOGCURRENTHOUR.Value)
'Add path and .csv to get full file name - note SRAM storage
LOGFILENAME.Value = "\SRAM Storage\" + LOGFILENAME.Value + ".CSV"
'Open log file or create new log file if there isn't one
LOGFILEHANDLE.Value = View.LogOpenFile (LOGFILENAME.Value)
If LOGFILEHANDLE.Value = -1 Then
LOGFILEHANDLE.Value = View.LogNewFile (LOGFILENAME.Value)
'Add Column titles to new file
View.LogPrintString LOGFILEHANDLE.Value, "DATE, TIME, VAL1, VAL2, VAL3"
View.LogNewLine LOGFILEHANDLE.Value
End If
View.LogSetUseComma LOGFILEHANDLE.Value, 1 ' Add comma after LogPrintValue (default)
'Log the current data
View.LogDate LOGFILEHANDLE.Value
View.LogTime LOGFILEHANDLE.Value
View.LogPrintValue LOGFILEHANDLE.Value, SIMTANK1.Value, 3
View.LogPrintValue LOGFILEHANDLE.Value, SIMTANK2.Value, 3
View.LogPrintValue LOGFILEHANDLE.Value, SIMTANK3.Value, 3
View.LogNewLine LOGFILEHANDLE.Value
'Close file so it doesn't get corrupted
View.LogCloseFile LOGFILEHANDLE.Value
'Check hour rollover, move all csv files to SD card
'This copes with SD card beinhg removed, since files remain in local
'memory until SD card is available, then all copies moved
'So also no issues with deleting files locally either
If LOGPREVIOUSHOUR.Value <> LOGCURRENTHOUR.Value Then
' Delete old files here
' View.FileDelete "\SDMemory\*.CSV"
View.FileMove "\SRAM Storage\*.CSV", "\SDMemory\", 0 ' Overwrite
' Use httcopy here to move to external location
End If
LOGPREVIOUSHOUR.Value = LOGCURRENTHOUR.Value

RE: QuickPanel Plus History Alarms to CSV

Andre Dicaire — Tue, 13 Aug 2024 15:15:15 GMT

DeltaV Alarms and Events are stored in the Event Chronicle A&E Database. This is a SQLExpress database that is accessed with Process History View. Process History view provides export functions to allow saving a filtered list to file. However, it does not have a mechanism to do this programmatically. It does provide the means to back up the database itself as a whole.

The Alarms and Events can also be accessed with the OPC A&E server, which is an additional license. This allows OPC clients to subscribe to the Alarm and Events for use externally to the DeltaV system.

Emerson Also has DeltaV Mobile which exposes Alarms and events via a Phone based Android or iPhone app for pushing targeted alarms to users.

The SQLExpress database can also be accessed directly via ODBC connection to query the database via scripting, but that is not a supported product feature. That is, it is not documented for that purpose, and that is why you don't find that approach discussed in the standard literature. There are existing posts in this forum that discuss accessing the database directly and how to build a SQL query to retrieve filtered data. (i.e. only alarms).

If you are looking to analyze the alarm system performance, Emerson has the AgileOps Performance Analytics software that provides this along with canned reports.

maybe is you shared why you need this, a more specific solution might reveal itself.

RE: Using Kepware to connect to Rx3i and QuickPanel+ HMI

Steve Ward — Wed, 24 Jul 2024 13:28:50 GMT

For the PACSystems RX3i, you can use SRTP or Modbus TCP. Latest CPUs support OPC UA. Support will depend upon CPU type and firmware version and may need enabling in the hardware configuration.

For the QuickPanel+, you can configure Modbus TCP as a server in the application. Another possibility is to use OPC DA via PAC Machine Edition running on a PC on the same network as the QuickPanel+. SNMP is intended for network diagnostics only.

See our Emerson Customer Centre at emerson-mas.my.site.com/communities for details and documentation.

Using Kepware to connect to Rx3i and QuickPanel+ HMI

sanchit.sahay — Wed, 24 Jul 2024 13:17:57 GMT

I am looking to connect to an Rx3i PLC, and a QuickPanel+ HMI (separate applications) using Kepware as proof of concept.

Which communication technology/driver would be optimal for communication and reading data from both these systems?

I have had success with the GESRTP driver for Rx3i, and I see SNMP can be used for QuickPanel+ HMIs but the Emerson/GE documentation on SNMP configurations is quite complicated and does not address any potential security risks or how to configure the panel with cyber safety in mind.

Is there an optimal way to connect to both of these devices? Any documentation/example videos (not specific to Kepware but any software would work)

A question about the applicability of PAC3I and PAC8000 products to high-altitude areas

Jack.Zhang — Tue, 04 Jun 2024 08:32:19 GMT

I only saw a description about the product's operating temperature in the manuals of Pac3i and PAC8000, but what I want to ask is whether high altitude areas have any impact on our products. Where can I find this relevant information?

RE: A question about the applicability of PAC3I and PAC8000 products to high-altitude areas

Steve Ward — Tue, 04 Jun 2024 11:35:40 GMT

So at 4,000m, the maximum temperature has to be reduced by about 7 degrees C. LT versions don't help for altitude as they don't do anything at the maximum temperature, only the lowest temperature (LT means tested to operate at -40 degrees C). However altitudes are associated with low temperatures (ie if you're at the top of a mountain it's usually colder than at sea level), so LT would help for this.

PAC8000 already has a -40 to +70 degrees C temperature range and the CPE400 has the same temperature range. PACSystems RX3i has a standard temperature range of 0 to 60 degrees C.

RE: A question about the applicability of PAC3I and PAC8000 products to high-altitude areas

Jack.Zhang — Tue, 04 Jun 2024 11:12:24 GMT

Thank you Steve. Your help has been invaluable. I now have a project that needs to be implemented at an altitude of 4000 metres. I'm planning to use either the full PAC3I range or a combination of PAC3I 400CPU and PAC8000 IO. I would like to know if the PAC3I LT wide temperature range can help to avoid some potential problems. After all, it seems that the PAC8000 might be more suitable. At the moment, I'm more concerned about potential problems with the PAC3I in this environment.

RE: A question about the applicability of PAC3I and PAC8000 products to high-altitude areas

Steve Ward — Tue, 04 Jun 2024 09:17:14 GMT

Altitude limits are defined by standards like IEC 61131-2. For PLCs, the altitude limit for operation is 2,000m. Above this equipment needs de-rating as the lower air pressure means that heat is not dissipated as well as at lower temperatures. Thermal derating of 1 degree C per 305m above 2000m is recommended to take into account the lower density of the atmosphere and its ability to remove heat from the system. So for example at 3,000m, the maximum temperature would be reduced from 60 degrees C to 56.73 degrees C for PACSystems RX3i and from 70 degrees C to 66.73 degrees C for PAC8000.

RE: Does PAC ME support logic debugging, breakpoints, step execution, etc?

Steve Ward — Fri, 10 May 2024 07:34:16 GMT

Thankyou for your feedback, I will discuss with our Product Management team.

As for downloads, make sure you have latest firmware and PAC Machine Edition. These support smart downloads where only the modified block is downloaded. PAC Machine Edition 10 also has much better performance than older versions. You can also use the Online Edit option to make changes and quickly test them, then accept or cancel.

Download via Ethernet is recommended, although this is not possible with legacy PLCs and CPUs. Latest CPUs support Gigabit Ethernet which improves download times and monitoring performance.

Does PAC ME support logic debugging, breakpoints, step execution, etc?

Matthew Love — Thu, 09 May 2024 13:48:26 GMT

I'm working on a product with PAC ME v10.2 and PACSystems RX3i devices.

I am trying to test and debug the logic. I am used to other software tools that allow a user to pause execution of the logic, set breakpoints, and proceed with execution on a literal step-by-step timeline.

Does any of this exist within PAC ME/RX3i? I do not see anything obvious in the tool ribbons.

RE: Does PAC ME support logic debugging, breakpoints, step execution, etc?

Matthew Love — Thu, 09 May 2024 17:04:47 GMT

Steve,

Thanks for getting back to me so promptly. I appreciate it. I'm impressed by your depth of familiarity with the platform.
It's unfortunate there isn't a better approach than the old school method of putting flags and triggers into your program, necessitating later removal and clean up. It's also especially unfortunate given how long it takes to download even a small change in programming.

RE: Does PAC ME support logic debugging, breakpoints, step execution, etc?

Steve Ward — Thu, 09 May 2024 14:14:37 GMT

To debug on your development computer, you will be pleased to know that Emerson will soon be releasing the PAC Machine Edition Simulator that will provide the capabilities that you are looking for.

To debug inside the controller, you can use a "divide and conquer" approach. This involves dividing a large application into smaller ones and testing and proving each section individually. One solution is to use the END function to end execution of the logic at the programmed point (execution of the remaining logic will not take place and the program scan will re-start at the beginning of the _MAIN program). You can program an END function at the beginning of the application and then move it towards the end of the application as you prove each section of the logic. You could also consider a jump to label to pass over sections of logic that you do not want to execute. Subroutines can be tested independently in a test application and then enabled in the main application once proven. During development, you can also use SETCOIL and MOVE functions to store interim values into a data table area where you can monitor them to ensure the status or output of the application is correct.

RE: Any way to force Analog Inputs for RX3i?

MichaelRichards — Wed, 20 Mar 2024 20:39:00 GMT

You can use Indirect Addressing or Variable Indexing of Arrays to programmatically change the Analog Input address.

For Indirect Addressing (@), the Value of the Variable is taken as the Memory Location to access.

For example, an example in ST Logic:

if Enable_AI_Force then
AI00001_INT := Index;' AI0001 is mapped to %AI00001
@AI00001 := AI_Force_Data_Value;' Write data value to %AI indicated in Index
end_if;

Or, if you create an AI_Data Array Mapped to start at %AI0001,

if Enable_AI_Force then
AI_Data[Index] := AI_Force_Data_Value;' Write data value to %AI indicated in Index [Index is 0 based...]
end_if;

So, there are a couple of ways to approach this.

Any way to force Analog Inputs for RX3i?

Matthew Love — Tue, 19 Mar 2024 15:11:27 GMT

I would like to simulate an analog input signal for simulation purposes.

I see I can easily do this for DIs, DOs, and AOs, but cannot see how to do it for AIs.

Is this possible?

Thanks!