7 Segment Display via PLC

Friend,

I have a analog signal input to the plc , i want to convert it and send it out to 7 segment displays unit, i think the communication for the 7 segment unit is ACSII. How should i send the signal to 7 segment display through plc?what type of communication device i need to applied?

I planning to use TCP/IP and convert it to RS 485 ( the display only have 9 D pin connector )


Regard

Boy - o - boy,

The display needs ASCII, you've got analogue, so you're going to take TCP/IP and convert it to RS485. Yup, sounds like that should fix it!

Let's assume your reference to RS485 is accurate - this defines the 'electrical' specification of your display. Let's also assume your reference to ASCII is accurate - this defines simply how each character is encoded.

Next we need to find out whether any communications protocol is involved, and if so which. Is there any identification in the documentation for your display which describes or defines a protocol? If not, let's assume there is no protocol - you just send each character in turn with no handshaking, error-checking, message-length calculations etc. If there is a specific protocol you need to start working out how to match this. Does your PLC have a driver for this protocol?

If we have RS485 at one end of the electrical link it would be nice to have RS485 at the other end as well. Does your PLC have a serial output port which supports RS485 wiring? If not can you buy an add-on module which does? If not, does it have another serial comms output port based on RS232 or RS422? If so, get an external 232-to-485 or 422-to-485 adapter. Or is this where your 'TCP/IP' reference comes in. Do you actually only have some kind of Ethernet port available? We don't want to use 'TCP/IP' as the protocol. I wonder if others could advise on sending pure ASCII strings out an Ethernet port. Is there a device which will take CAT5 UTP cable in and give out RS485 at the other end? Sounds like this might be needed.

After all this, reading in the actual analogue value as an INTEGER then converting it to a STRING or series of CHAR data types sounds like the easy bit!

Good luck

Ken.

Thanks Ken,

If the display is no protocol, how should i to communicate with plc?

how to configure it?

regard

Teh

If there is no protocol used, I would hope/guess/pray that your PLC has some kind of SEND or PRINT instruction that you can use with the comms port to transmit a memory address containing the ASCII code for a character.

The final question "how to configure it?" is the $64K one - I don't even know what "it" is yet!

In this forum, you are allowed to use names, makes, models. It can help if you give a little more information.

Regards

Ken.

The chips is key.

If does not it have as identify the DISPLAY. Do a research. the Chips control off diplasy LCD/ LEDS they are the equals codes. They are responsable by store, map of letters, phrases, communication. Therefore, the way of carry and startup stayed standardized. Always they are, programmed by 8bits or 4bits + 4bits (MUX) as has 9 pines, possible be 4 bits + 4 bits, for line of data.
Does not have to descrition of the pinout?
I have this stuff in Portuguese, researches for "LCD comunication (and) protocol" lives (LCD 16 lines 20 lines) Knowing, is information, can test without risk (mainly pinout and signals Level TTL)
OR
7 segments, not has letters.Ok, manufactures low prices this schematic, and sometime change type display
OR
simple chips SHIFT-REGISTER, send serial date update display. The meanses fisics of communication, they can be them cited previously. Good luck