Match the Do-more driver and register family in your HMI

One driver, one register family

Two paths, two families, no overlap:

On Do-more and BRX processors the Modbus family holds no copy of your working data. The ladder program moves each value into the MIR, MLR, MIC or MLC registers before a Modbus reader can see it. The Koyo family works the same way: the value has to be in DLV, DLC, DLX or DLY, not only in the registers your logic uses internally.

One rule follows. Never convert a tag between the families by editing its prefix. A DLV number and an MIR number live in unrelated address spaces, so a renamed tag can point at empty memory while looking correct on screen. Rebuild the tag against the family of the driver you selected. On another controller line the same job is mapping CLICK PLC addresses to Modbus for an HMI panel, where the addresses likewise change with the protocol.

What you need before you configure

• The driver list of the installed HMI software. Drivers live in the project's communication setup, and the list is version specific, so read it on the machine that will run the project. Check the panel driver list before tuning serial settings explains why this comes before any baud rate or station number work.
• The controller memory map. Print or export the register map from the Do-more Designer programming software, a free download with a built-in simulator, so you can run the ladder mapping with no machine attached.
• The data list. One line per value: name, PLC-side register, read or write, and the data type the driver will use.
• The network parameters. For Modbus TCP, the controller's address and the listener port it uses.

Set the connection up in stages

1. Choose the path from the driver list, Koyo driver or Modbus, and write the choice at the top of the data list. Every tag inherits it.
2. Put the data in the matching family. On the Modbus path, add the ladder moves that copy each value into MIR, MLR, MIC or MLC, download, and watch the moves execute in the data view. On the Koyo path, place the values in DLV, DLC, DLX or DLY.
3. Create the HMI connection with the parameters that driver needs: for Modbus TCP, the controller address and TCP port 502, the default Modbus TCP listener port; for the Koyo driver, the settings its documentation prints for this controller.
4. Add read tags only, no more than ten, one per data type you will display. A mapping error then shows up as one bad tag instead of a screen full of noise.
5. Qualify the reads. Open the controller data view beside the HMI screen, make each value change, and confirm both displays agree through the change.
6. Add one write tag. Pick a point that is safe to exercise with the machine in a safe state, and never make a production start command or an interlock reset your first write test.
7. Confirm the write lands: the controller receives the value, the logic acts on it, and the HMI reads the result back.
8. Power-cycle the controller and the display, then repeat the checks from step 5. A tag map that only works until the first restart still needs work.

Example: a filler line status screen

An operator station reads five values from a Do-more controller: filler speed in parts per minute, a shift counter, a batch counter, an active fault code and a running state. It writes one command, a counter reset. That is six data points, five reads and one write.

The installed HMI lists a Modbus TCP driver and no Koyo driver, so the path is Modbus and the family is MIR, MLR, MIC and MLC. The ladder gains five moves, one per read value, and the reset command lands on one Modbus-family bit. Round one qualifies the five read tags against the data view while the counters tick. Round two exercises the single write with the line stopped and its guard closed.

Size the numbers for the distance. The screen stands about 8 ft from the operator. The planning figure is 30 ft of viewing distance per inch of capital height, FHWA, so the floor for these values is 8 / 30 = 0.27 in capitals. Fast reading calls for 20 ft per inch: 8 / 20 = 0.4 in. Line spacing at 1.7 times capital height gives 1.7 × 0.4 = 0.68 in, and five status lines take 5 × 0.68 = 3.4 in of text height. A 15.6-inch 16:9 panel offers about 7.6 in of vertical space, 15.6 × 9 / 18.36, so all five values fit with room left to set the fault code line at 0.6 in capitals, a size that reads from 12 ft at the safer figure, 0.6 × 20 = 12.

How to check it worked

A green connection indicator is layer one. The pass condition is agreement: the value on the screen matches the register in the data view while that value moves.

• Set and clear the fault code and watch both ends follow.
• Let a counter run and confirm the HMI tracks it digit for digit.
• Exercise the write again after the restart check.

Reads that fail or return nothing useful while the link stays green are the signature of a family mismatch: a Koyo-driver tag pointed at an MIR number, or a Modbus tag pointed at a DLV number. Check the family before you touch a single network setting. A project that must keep a serial link alongside Modbus TCP follows the same one-path-per-connection rule; the wiring pattern for running one HMI panel on serial and Modbus TCP together is covered separately.

The decision for each case

Recommendation: use the Koyo driver with the DLV, DLC, DLX and DLY registers whenever your HMI's driver list names that driver for this controller; it is the native access path. Use Modbus with the MIR, MLR, MIC and MLC registers when the list has no Koyo entry, and budget the ladder moves that put each value into that family. In both cases keep every tag of one connection in one family, qualify reads before writes, and test the single write on a point that is safe to exercise.

If the cell also needs a board that plays prepared notices instead of live tags, shop-floor signage screens do that job from a memory card with no controller connection. They are content displays; the live operator interface stays on the HMI.

Questions