As a novice in Rockwell software, I have received some basic training but lack advanced knowledge. At my company, we rely on Reliable products for HVAC programming. Our current challenge involves programming a Make-up Air Unit to activate based on commands from an HMI interface. For instance, an operator may choose to start the MAU between 9 am and 2 pm on one day but restrict it to 8 am to 10 am on another day. While I am familiar with using WallClockTime, I am unsure of how to compare DINT tags from the HMI with GSV values. I have attached a sketch of the HMI for reference. Explore more about this topic at Imgur, where you can find a variety of entertaining content ranging from funny jokes to viral videos.
In a forum post, Duchx2 expressed uncertainty about comparing DINT tags from the HMI with GSV values. The Rockwell Automation website offers a set of routines for handling 64-bit WallClockTime values in Logix programming. It is crucial to align the time representations from both systems by ensuring they share the same zero epoch, time zone, and interval per count. The HMI's DINT value likely indicates a 32-bit count of whole seconds since the Unixâ„¢ epoch, while the Logix GSV WallClockTime object represents a 64-bit count of microseconds since the same epoch. To prevent rollover issues and ensure accurate comparisons, moving the values to LREALs with 53 bits of precision could be a practical solution. Considerations such as drift, clock synchronization, and required accuracy should also be taken into account for a successful comparison process.
Converting the HMI DINT into a readable date and time format, such as year, month, day, hour, minute, and second, allows for comparison with the GSV WALLCLOCKTIME.DateTime DINT[7] from Logix. However, this comparison can be complicated and difficult to manage.
Thank you for your response. I find the concept of utilizing DINT tags in Logix Designer rather complex for my level of expertise. My plan was to create a DINT tag named "Monday" with sub-divisions such as Monday.8 for 8am, Monday.9 for 9am, and so forth. By assigning values to these subdivisions, such as 1792 for the time period from 8am to 10am, I can then compare it to the WallClockTime. As someone who is self-taught, I will begin by delving into the suggestions you have provided.
I was initially confused about the application. Are you suggesting having 7 DINTs, one for each day of the week, with the first 24 bits of each DINT representing hours of the day? Essentially, the PLC would only need to identify the current day of the week to determine which DINT to reference and which bit to check for the current hour using DINT[3] from the WallClockTime/LocalDateTime GSV. It's actually a clever approach. Instead of converting the day of the week and hour operator input into a seconds-since-epoch DINT value on the HMI side, focusing on the day of the week could streamline the process. You can search this forum or the Rockwell site for "day of week" to find a suitable AOI. Alternatively, by knowing that the 1970-Jan-01 epoch fell on a Thursday, you could divide the GSV WallClockTime/CurrentValue by 86,4000,000,000 (µs/d; truncated) to calculate days since the epoch, then determine the day of the week offset from Thursday (0=Thursday, 2=Friday, ..., 6=Wednesday) or adjust it by 4 initially to find the offset from Sunday: Code: GSV WALLCLOCKTIME CurrentValue wallclock_LINT ### Obtain CurrentValue of WALLCLOCKTIME, µs since epoch MOD wallclock_LINT 86400000000 working_LINT ### Determine current day in µs SUB wallclock_LINT working_LINT working_LINT ### Truncate CurrentValue to start of today DIV working_LINT 86400000000 working_LINT ### Calculate today's offset from epoch in days ADD working_LINT 4 working_LINT ### Determine today's offset from Sunday Dec. 28, 1969 in days MOD working_LINT 7 working_LINT ### Find day of the week, offset from Sunday, in days
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It sounds like you're doing some really interesting work with HVAC programming and the Rockwell software! It's definitely a challenging task programming the Make-up Air Unit to activate based on such specific time intervals, especially if you're relatively new to the system. With regard to comparing DINT tags from the HMI with GSV values, I would suggest setting up comparison logic to check if the WallClockTime is within the range defined by your DINT tags. This could be achieved by using an 'AND' Logic instruction that keeps the MAU in operation when the time is in the defined range. Also, take a look at using the 'Masked Move' function for separating out your HMI time inputs. Good luck, and don’t hesitate to ask if you have further questions!
Hey there, it's great to see you taking initiative to expand your knowledge in HVAC programming using Rockwell software! For comparing DINT tags from the HMI with GSV values, you might need to use a logic comparison instruction. To do this, you can use geq instruction (greater than or equal to) or leq instruction (less than or equal to) depending on your use case. This could help you match the command input on the HMI with the GSV value. Remember, the key here is to structure your programming well, so take step-by-step approach and check at each stage. Don't be afraid to seek help from experienced colleagues or online platforms when needed. Happy programming!
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Answer: - To program a MAU using Rockwell Software, you can start by familiarizing yourself with the basics of the software and then gradually delve into more advanced concepts specific to HVAC programming.
Answer: - You can set up the programming logic to trigger the MAU based on the commands received from the HMI interface, such as utilizing WallClockTime and comparing DINT tags with GSV values.
Answer: - Yes, you can program the MAU to activate at different times on different days by incorporating conditional statements in the logic based on user input from the HMI interface.
Answer: - You can explore online platforms like Imgur for a variety of content, but for specific technical guidance on Rockwell Software programming for HVAC systems, you may want to refer to official Rockwell Automation documentation or participate in relevant forums or training programs.
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