Van

Forgive my ignorance. I"m not a seasoned PLC programmer. I was just using the schema as an example. However, that link was sure helpful, thank you.

Excellent! Thank you for your assistance! And I used ASC(086) to convert my resultant: ASC SUM_RES #0030 XMT_DATA_CS it worked!

Equipment: CJ1M-CPU11 I am trying to figure out how accomplish this using ladder logic. The Omron instruction FCS(180) is similar to my needs but doesn't appear to perform the same math operation (I don't get the same result). I think I have to write this one. Question One: Best method to perform the math? Which instruction would you recommend? Question Two: What really stumps me is the conversion of each digit of the last byte into an ASCII code.

I am using a CJ1M-CPU11 (and 12) Version 3.0. Does this present a problem? That is what I am trying to do: initially populate the data memory. Example: ON PLC Start do: set "MyTestSymbol" = "TextData"

I am a PC programmer and I know some basic PLC programming. I am part of a project where I am writing PC server code (in C/C++) to communicate with Omron PLCs. I have written PC code to communicate with PLCs before using the CX-Server Lite OCX (Active X) component in VB6 however that will not work in this project. There is no GUI on the PC side (it's a console/service application). I am working with our vendor and Omron in trying to obtain an API/SDK to communicate with the PLCs however we seem to be having a communication breakdown. Either I just don't understand what they are saying or they don't understand what I need. They keep referring me back to the ActiveX component and that just won't work in this case. Someone recommended this site. I need the ability to communicate to one or more PLCs to send commands to; query states of; and received notices from Omron PLCs (CJ1M CPU12). We are using C/C++ on the PC. What is the recommended communication method and where do I obtain (or what do I ask for) in a PC API/SDK to permit the PC to communicate with a PLC and vice versa? If there isn't an API/SDK then is there a document or white paper I should review? Third party API/SDK are acceptable if they work well. I have been reading a lot of posts in the forum however I am not a PLC expert and thus am unfamiliar with a lot of the terminology used here. Please treat me with kid gloves! The PLCs have serial (Toolbus?) and Ethernet connectivity. I would prefer network connectivity for greater flexibility. If anyone could point me in the write direction I would appreciate it.

I do have basic PLC ladder logic experience. I have programmed several PLC ladder logic programs but nothing very sophisticated. For this project we do require a PC to maintain a SQL database of the platforms and their payloads. The PLC just isn't capable of doing what the PC can do in terms of storing, sorting, anticipating, analyzing, etc. There is a lot more to the server code than what most people think. IMHO that's just not what a PLC is designed for. A PLC is finite state machine for which it performs magnificently. FYI, we have determined that MODBUS isn't the way to go. Ah ha! Now we are getting somewhere. Thank you very much! So we can develop our own messaging system using the SEND RECEIVE DATA FUNCTION BLOCKS? This is perfect! We will look into this. Is there a certain Omron publication that you would recommend reading? Whitepapers? Also, does any know which sample code in PC and PLC that uses these methods?

The application is a material handling device. We move platforms containing a payload. Right now, it appears we will only have a single PLC using remote I/O. The PC server application maintains the location of the platforms and the information about their payload (if any). The PC server application instructs the PLC to GET a platform from or PUT a platform into a location. The command from the server is simple: SOURCE and DESTINATION. The PC server wants basic updates as to the current state of the system such as: arrived at source level; getting platform; got platform; arrived at destination level; placing platform; platform placed; etc. The frequency is considered quite long - a period of seconds up to a minute. So, there is no millisecond updates required. The PLC knows what to do to get or put a platform. It just isn't smart enough to keep a database of what is where - which is where the PC server comes in. We would prefer to stay OUT of the polling mode business and have the PLC actually send updates to the PC server as the PLC state/task changes. If an error occurs, the PLC needs to notify the PC server with an error code (part of the PLC code).

Thank you for your replies. I have made an inquiry to the above link. I have stumbled onto Modbus ( www.modbus.org ). Will Modbus satisfy our requirements? What are the Pro's and Cons of using Modbus? Does anyone know if the CJ1M CPU12 natively support Modbus?