FactoryTalk View ME Macro: Split 8-Digit Input to PLC-5 N70 Array

Problem Overview

An operator on a PanelView Plus terminal must enter a single 8-digit decimal value (e.g., 34567890) and have the HMI software distribute each digit to a separate integer file word in a PLC-5/40E controller. The target is integer file N70 with elements N70:0 through N70:7, where the most significant digit lands in N70:0 and the least significant digit (ones place) lands in N70:7.

This is a classic PLC-5/40E sizing limitation. A PLC-5 integer file element is a 16-bit signed word with a maximum positive value of 32767. An 8-digit number such as 99999999 exceeds this by a factor of ~3,050 and cannot be stored in a single N word. FactoryTalk View Machine Edition User's Guide (VIEWME-UM004) does not provide a direct single-tag-to-array digit splatter, so the conversion must be performed either:

1. In an HMI-side macro (VBScript) using integer division and the Mod operator, or
2. In PLC-5 ladder logic using the AEX (String Extract) and ACI (ASCII Convert to Integer) instructions against a string tag such as ST10:0.

The HMI-macro approach is the most portable and the one that ships out of the box on a stock FactoryTalk View ME runtime; the string approach is fragile because the AEX/ACI combination requires precise mid-string index handling and is sensitive to leading-zero padding.

PLC-5 Integer Constraints and Address Mapping

Because every target word holds a single decimal digit (range 0-9), the only required math is a base-10 decomposition. There is no need for BCD (D-file) handling, hexadecimal conversion, or 32-bit long-integer support inside the PLC-5 scan.

Prerequisites

• FactoryTalk View Studio v5.0 or later (catalog 9701-VWMx), with the runtime image deployed to a PanelView Plus 6, 7, or PanelView 5500 terminal.
• RSLogix 5 (or Studio 5000 with PLC-5 add-on profile) to confirm the N70:0 through N70:7 addresses exist in the data table.
• RSLinx Enterprise / RSLinx Classic with an active topic to the PLC-5/40E.
• A working numeric input cursor configured in the HMI display that writes to an HMI memory tag of type Long or DINT with a 0-99,999,999 range.
• A second HMI button or DisplaySetting shutdown trigger to fire the split macro.

Solution 1: HMI-Side Modulus Macro (Recommended)

The most reliable method is a single VBScript macro fired on the shutdown of the numeric-entry pop-up display (or from a dedicated Transfer button). The macro reads the 32-bit HMI tag, applies integer division and modulus 10 to extract each decimal place, and writes one digit per N70:x word.

Macro Code

Sub SplitToN70
    Dim v As Long
    v = BigInput.Value          ' 32-bit HMI tag, range 0..99999999

    ' Int() forces truncation so 9.999 does not round up to 10
    N70_0 = Int(v / 10000000) Mod 10   ' ten-millions digit (MSB)
    N70_1 = Int(v / 1000000)  Mod 10   ' millions digit
    N70_2 = Int(v / 100000)   Mod 10   ' hundred-thousands digit
    N70_3 = Int(v / 10000)    Mod 10   ' ten-thousands digit
    N70_4 = Int(v / 1000)     Mod 10   ' thousands digit
    N70_5 = Int(v / 100)      Mod 10   ' hundreds digit
    N70_6 = Int(v / 10)       Mod 10   ' tens digit
    N70_7 = v Mod 10                  ' ones digit (LSB)
End Sub

Why Int() instead of the -0.5 trick

The original (value % 100)/10 - 0.5 approach used a subtraction to defeat implicit rounding when the HMI runtime converted a real to an integer word. That workaround silently corrupts legitimate zeros. A pure Int(value / divisor) expression always truncates toward zero, so a ones digit of 0 is written as 0, not as a negative stub. VIEWME-UM004 documents the Int, Fix, and Mod built-ins in the VBScript reference appendix.

Sample Verification (input 34567890)

Solution 2: PLC-5 Ladder String Method (AEX + ACI)

Rockwell's FactoryTalk View ME documentation set cross-references PLC-5 string instructions. If you would rather do the split inside the PLC scan, the operator enters the value as a string (e.g., ST10:0 = "34567890") and the ladder pulls each character out.

PLC-5 Ladder Snippet (Rung Description)

1. Rung 1: AEX ST10:0 ST10:1 0 1 extracts the first character of the entry into ST10:1 (string of length 1).
2. Rung 2: ACI ST10:1 N70:0 converts the ASCII '3' (hex 0x33) to the integer value 3 and stores it in N70:0.
3. Repeat for indexes 1..7, writing the converted values to N70:1 through N70:7 in order.
4. Add an EQU compare on ST10:0.LEN equal to 8 to enable the conversion; otherwise left-justified short entries will leave trailing words stale.

Solution 3: Pure PLC-5 Divide-and-Subtract Ladder (CompactLogix Heritage)

The pattern of divide-then-multiply-then-subtract in ladder logic works in CompactLogix but is not native to PLC-5 because PLC-5 has no 32-bit integer data type. Skip this approach on a PLC-5/40E.

HMI Tag Configuration

Numeric Input Cursor Settings

• Tag: BigInput
• Minimum: 0
• Maximum: 99999999
• Input style: Decimal, no thousands separator
• Display on shutdown: Run SplitToN70 macro (so the operator only touches one key, not two)

Step-by-Step Implementation

1. Open the FactoryTalk View Studio project that targets your PanelView Plus terminal.
2. In the project tree, expand HMI Tags and create an HMI memory tag named BigInput with data type Long (or DINT) and initial value 0.
3. For each of N70:0 through N70:7, browse to the PLC-5 device and add a tag alias. If you prefer one continuous block, add N70 as an array of eight Int tags and reference N70[0] through N70[7] in the macro.
4. Open the display where the operator enters the 8-digit value. Insert a Numeric Input Cursor Point bound to BigInput. Set Min = 0, Max = 99999999.
5. Click the cursor, go to Properties → Behavior → On Shutdown, and attach the SplitToN70 macro. (If you prefer an explicit button, drop a Command button on the display and set its Press - Run Macro action to SplitToN70.)
6. Paste the macro from the Macro Code section above into the project's Macros folder. Compile and save.
7. Create eight Numeric Display objects on the same screen bound to N70_0 through N70_7 so the operator can see the split values immediately.
8. Download the runtime image to the PanelView Plus terminal and cycle power.
9. In RSLogix 5, place the data monitor on N70:0..N70:7 to verify the writes.

Verification and Commissioning

Use the following test matrix. Each row exercises a different combination of leading-zero, mid-zero, and trailing-zero positions to prove that the Int-based macro does not lose zeros.

For each test, perform the entry, dismiss the pop-up, and confirm in RSLogix 5 that the eight N70:x values match. If a value is off by one, suspect a rounding error and re-check that you used Int(...) rather than implicit conversion.

Troubleshooting Matrix

Field-Proven Caveats and Edge Cases

• Leading-zero handling. The PLC-5 integer file has no notion of "leading zero." An entry of 00000042 is stored as N70:0..N70:6 = 0 and N70:7 = 42 only if you treat N70:7 as the ones place and the rest as zero. Decide the digit-to-word mapping up front; do not flip it after commissioning.
• Sign. Never use this pattern to store a signed value. The HMI BigInput must be declared unsigned-equivalent by clamping the range to 0-99,999,999 in the numeric input.
• Endianness. PLC-5 stores integers little-endian, but you are writing one digit per word, so the question is moot at the bit level. It is a real concern only if you later pack two digits per word using BCD.
• Performance. The macro runs once per pop-up shutdown; even a 400-MHz PanelView Plus 6 executes it in under 5 ms. No scan-time impact on the PLC-5.
• Multilingual numeric formats. Some locales display 34,567,890 with a thousands separator. Set the numeric input cursor to No Separator to prevent the runtime from rejecting the comma.

Related PLC-5 Instructions (For Reference)

FAQ