Internet PLC Forum

Although TRiLOGI has the SETLED command, it was never implemented in the hardware.

What is the interface to drive your 4 digit LED? Some LED has RS232/RS485 interface which the PLC can send data to be displayed. If your LED is just plain LED segments without driver, then you may use the PLC output to drive the LED segments if it is a common anode type. You will need current limiting resistor to limit the current to the LED. Note that in this case, each digit requires 7 or 8 (if including decimal) outputs.

You can then construct the segment pattern that correspond to each digit 0..9 by store them into a lookup table in memory and when you need to display a number, just take the corresponding output pattern to send to the outputs to drive the LED segments.

First of all, the T100MD+ verion 5.x software does not allow you to upload program from the PLC so you are safe.

DOS TRiLOGI version 4 has the ability to upload the ladder program but not the custom function from the PLC.  However, you can use put in a program upload/download transfer password using TL41.exe which can prevent unauthorized attempt to upload the ladder logic and it also restrict transfer of new program to the PLC without the password.  This capability was not brought to Version 5.x to avoid confusing user with the TLServer username/password system.

TRiLOGI available for free download from our website are educational version and do not have ability to communicate with the PLC so that should not be not of concern to you.

You are right that READMODBUS is implemented using MODBUS function 03 and WRITEMODBUS is implemented using MODBUS function 16. These two functions are considered MODBUS Level 1 functions and are the most fundamental MODBUS command that any MODBUS master has to support.

If your device requires other function, then you can implement it using INCOMM, OUTCOMM and CRC16 (for PLC with firmware revision r44 and above only). We have posted a sample program that you can download from the following link:

http://www.tri-plc.com/trilogi/modbusFunction04.zip

This sample implements the function 04 and is tested to work with a slave T100MD888+.

Does the PLC output appear as ON during online monitoring? If online monitoring shows that your output is off, yet the output LED turns ON, it means that the output driver has probably blown.

The output drivers on T22H-npn are controlled by the ULN2003A. You can try to swap the ULN2003A that controls output 1-4 with the other chips and see if the output problem has shifted. If so, it confirms that the output driver is fried.

The most likely reason for the output driver to blow is over current. Wrong polarity connection to the PLC's power supply input can also knock out the output driver.

You can purchase the ULN2003A driver chip easily from any Radioshack or any local electronics store,  or you can purchase it from us.  Please send your request to sales@tri-plc.com if you wish to purchase the ULN2003A chip.

Write cycles is per memory location. So if you write 8 data to 8 different locations, each location only undergoes 1 write cycle.

When you transfer program to the PLC, each complete transfer is considered 1 cycle.

Anyway, the program EEPROM and data EEPROM occupies different memory locations so they are independent of each other.

I tried out your program and managed to get pulses from both output #5 and #6 simultaneously. Did you observe the pulse output from both your output #5 and #6?

Since I don't have two stepper motor driver on hand  I observed the wave forms on an oscilloscope but did not notice any unusual pattern. So I both channels should be able to work simultaneously. They are of different direction since one is +ve direction and another in -ve direction so their respective direction output (#1 and #2) will be turned ON/OFF accordingly.

I believed you have emailed the same question to us, but our reply to your email address was unsuccessful. The reply is the same as below:
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Please read page 1-1 of the User's Manual which show
you the mapping of the pulse measurement input with the
physical input. Please note that PM channel #1 is input
#3 and PM channel #2 is input #4. So your pulses must
feed through input #3 and #4 for their respective PMON.
Also the voltage of the pulse input must be compatible
with the PLC input. Did you observe that the input
logic status where the pulse stream is connected has
been turned  ON and OFF repeatedly when performing
online monitoring?

It is unbelievably easy to perform frequency measurement using the T100MD pulse measurement capabiliy . All you need to do is to  execute the PMON 1 function once to enable input #3 as a frequency measurement input. Once enabled, you then simply use the PULSEFREQUENCY(1)  function to read the frequency of the pulses appearing at the input #3. E.g.

   F = PULSEFREQUENCY(1)
  SETDAC 1,F       ' direct output without scaling.

You can measure from 1 Hz to 10000 Hz. You can either execute the above function every scan or use a clock pulse to periodically read the pulse frequency.

The value read into F can then be scaled to whatever value you want or output directly to the analog output using the SETDAC command as shown in the example above.

However, IMHO, using the analog I/O as interface between the PLC and the microcontroller is not exactly  the best method. You could actually design your own communication protocol in the microcontroller so that the frequency value read by the T!00MD+ PLC can be transfered to the microcontroller using the RS485 port without incurring any potential inaccuracy introduced by the analog interface.