Hello,

Yesyen

Hello,

I have CM 1241 (RS422/485)module and rs485 to rs232 converter. And need to connect it with two weighing indicators. Indicators has rs232 port that supports ASCII. 

Is it possible to connect both weighing indicators to one CM 1241 (RS422/485)module?

If yes which blocks can I use for this connection in tia portal. Right now I found RCV_PTP block. But with this block as I understand I can connect only one of them.

no, it is not possible in this case because your 2 weighing machines hasn't addressing probably so it is not possible destinate each different device, although you have RS485->RS232 converter. You can solve this only with 2x ETH->.RS232 adapter, each ETH Port will act as TCP Server and then you can physically differ 2 independed connections to 2x different RS232 devices. S7-1200 will be then TCP Client so you need access all things like pure OUC via TCP, basically use of TCON, TSEND or same but _C blocks, as you need. This adapter does all conversion business then internally, from your point of view you're communicate simply just like over TCP, nothing special. Physical RS485 converters have not addressing, only for special protocols in case so it is not helpful here.

You can also solve this with next RS232 module or next RS485/422 module (with also RS485->RS232 adapter) on S7-1200 if you have them, then you don't need that ETH adapter solution, my mentioned.

Hello,

PROBLEM!!!!!!!

As I can see in S7-1200 Conference, different informations are there compared here. Your description there:

user

Hello ,

I have 2 weighing indicator(CI-5200A) that supports modbus rs232 ASCII. In the plc(S7-1200) side I have CM 1241 (RS422/485) module and between plc and indicator I have RS485 TO RS232 converter.

My question is how can I communicate one master RS485 to indicator slave rs232 through RS485 TO RS232 converter.

I tried to do it via block RCV_PTP . But with this block I can make only one master and one slave.

Look especially at bold informations inside quote. In this case it is really important to know exactly cfg and protocol available at your weighing devices. Pls check this again carefully because from your informations here in this Topic, Modbus RTU or Modbus ASCII informations are missing. Then in this case and if it is really so, my recommendations about ETH adapter are not helpful. Pls provide again very clear informations what exactly model with exactly comm protocol you have.

In my opinion, it is strange that device with RS232 will support Modbus RTU/ASCII protocol because RS232 devices are PtP capable and can't be addressed, simply it is not required because of PtP capability. Yes, some devices are still on market but multi number of devices on bus are limited. One recommendation for you, don't post twice posts with your problem, here is more problematic because you didn't post same informations, this is more problematic then.

Update: to my experience with weigh devices generally, I expect maybe std ASCII not Modbus protocol but pls provide this information for sure to give better solution.

Hello,

although I see that device ID is presented inside frame, I recommend to have next CM RS485/422 with conversion adapter to RS232 or alone CM RS232 module. I think that CM RS232 can be cheaper than RS485/422 and also one adapter for conversion. It is as I've expected, std ASCII protocol. It's up to you, all depends of course to your free left positions slots of CPU to insert next CM. Good luck.

Hello,

really hard to help you exactly. There are so much factors that can affect your communication functionality.

1. wrong wiring, especially you have (as you said) RS422/485 module and also connected with RS232 converter. I expect maybe check LEDs on adapters for first so if there is steady LED ON without any send/recv, it points probably to not swapped Data+ and Data- wires on one of 2 sides of RS485 line. Generally rule is -> TX->RX and RX->TX signals connected.

2. we don't know how you have configured your weighing device because it can be configured with 2 modes (to my experience generally). One is bidirectional messaging or only weighing device is set as cyclical send device with defined send cycle. You need look carefully to documentation.

3. I've never used CHAR data type for serial communication at my history, my preffered BYTE was used. To this data type I did my conversions as were required. You need pay attention especially at special control chars values (ASCII code 0 to your used like CR, LF generally). Imagine how can be char NULL be presented like char. These special control chars are with lead $ char. Anyway, my opinion is that you have problems with thiese special control chars because you've set them as chars but CR or LF are special chars with one code value. Look again carefully to ASCII table what value decimal or hex they have. One of them has dec 13 but you need find them as char representation -> with lead char $. Next idea is that in case you need send known legth of chars as send sequence, try count your send buffer if it has that expected number of elements, as documentation describes. It has? I think no. End now next idea, ok, I see your blocks but in case yo need send something to weighing device, where is your SEND block? Can you better describe that my expected 2 mode functionality of this device, what you have set there exactly? Now it is really little chaos what exactly you do and how is device configured.

4. you need carefully look programatically at output parameters of blocks - DONE, ERROR, STATUS and check values to have information about processing. Description of codes are inside help of each used comm block.

Again one important tip which can be used every time prior any programming with PLC. Use some PC adapter/cable connected to weighing device and run some good PC app like Hercules, you can then easy check messaging, how it is working, what messages with what inside structure are proceeded and better then prepare PLC code. You've selected most problematic way as initial step.