How can MII Pull data from weighbridge system using RS232 port

[former_member703282]

Hello Friends,

We have a requirement to connect MII to weighbridge system which uses RS232 port. We have a transaction at S\4 HANA which requires the weight of truck. On the transaction screen there is a button to fetch the weight which will invoke a MII webservice (MII BLS Transaction) which in turn connect to weigh bridge system to pull the weight. This info will return back to S\4 as a response of webservice. Here my question is, how MII can pull the data from weighbridge system. As per my knowledge Pco socket connection can be used to connect RS232 port. But my BIG question is, do we have any method to pull the data (receive) from weighbridge system. I had checked the Pco query documentation and found CALL SEND(address=’127.0.0.1’, port=’20000’, message=’Hello World’); method to send the data. But my requirement is to pull the data. Is there any limitation to pull the data? Do we need to change the design and let weighbridge system to push the data to Pco which can be send to MII as a notification.

Any help on this very much appreciated.

SAP MII version 15.3

SAP Pco 15.4

Thanks

Shaji

[Kevin_Hunter]

Hi Shaji,

TCP/IP isnt the protocol either its a transport layer, for example OPC UA, ModbusTCP, Websockets etc all use TCP/IP as the transport layer but the protocols are different.

Also as mentioned you will need hardware to convert the RS232 interface to an ethernet interface as TCP/IP is not possible with RS232.

Examples are : Moxa Serial Servers https://www.moxa.com/en/products/industrial-edge-connectivity/serial-device-servers

Brainbox Ethernet To Serial servers http://www.brainboxes.com/ethernet-to-serial

Thanks

Kevin

[former_member703282]

Kevin,

Thanks again.

I am checking with my client to see if there is any hardware to convert RS232 interface to ethernet interface. In case if there are no such hardware, what are other options to connect? Is it mandatory to have that hardware?

Thanks

Shaji

[Kevin_Hunter]

Hi Shaji,

This all depends on the protocol.

If its Modbus RTU then you need a PC located next to the weighbridge then you connect the RS232 port from the weighbridge to the PC and install PCo on this PC. Nowadays this is actually harder than is used to be as most PCs don't have an RS232 port anymore (they were replaced by USB ports!) so you may need a serial to USB adapter. You also need to check if the RS232 port is a 9pin D-Sub or a 25pin D-Sub, then is it male or female and finally is it null modem, this dictates the cable between the port and the PC !!

If its not Modbus RTU then yes you need the hardware unless you want to write your own custom PCo agent that can access the serial port of a PC (same hardware issues as above).

Since this is serial data you need to fully understand how the messages are formatted so that you know when the message ends ! For example are the messages a fixed length or are they terminated with a particular character/s.

My personal recommendation is that you ignore the hardware for the moment and first priority is to understand the protocol, once you know the protocol we can work out if PCo supports it. Once we know this then look at the hardware.

Thanks

Kevin

[former_member703282]

Kevin,

A million Thanks for the detailed information. Your inputs are much appreciated

[former_member703282]

Hi Kevin,

We have procured a device (linked mentioned below) in order to convert RS232 format to Ethernet. But unfortunately it is getting converted to a COM3 port only. As you know in Pco we need a IP address and port number to create a Socket source. Any idea how can we find the Ethernet server IP address and port number from this device.

Link of device

Thanks in advance

Shaji Chandran

[Kevin_Hunter]

Hi Shaji,

For some reason the link you provided doesn't take me to a product it just goes to the home page, can you tell me the model number I will look it up.

In general these type of devices come preconfigured with a static IP address which is often printed on the case of the device or in the documentation provided with the device. However the static IP tends to be a private 192.168.X.X IP address which is not compatible with a corporate LAN which is typically 10.X.X.X . You will have to read the instructions provided with the device and work with your network infrastructure team to configure the device to connect it into your network.

Once connected your network team will be able to tell you the IP address, then you can access its internal web server to configure the port etc.

Thanks

Kevin

[former_member703282]

Hi Kevin,

Thanks for the quick response. I do agree there was an issue with link earlier, sorry for the same.

Please try with this link

Thanks

Shaji

[Kevin_Hunter]

Thanks, the new link works. The bad news is that you have purchased the wrong device, this is a serial port replicator which is why it is appearing as a com port on your machine. You need a serial to ethernet serial server.

Kevin

[Kevin_Hunter]

Hi Shaji,

RS232 is the hardware interface, what is important to know is what is the protocol being used to transmit the data via RS232.

For example it can be Modbus RTU , or plain serial data?

If its plain serial data you may have to use an inexpensive serial to ethernet adapter to convert it into TCP Sockets.

As for pulling data, you send a message requesting the data and the device responds to your message. Or the weighbridge streams the data to you, this all depends on the actual weighbridge capabilities.

Apologies for being a little vague but without knowing the communication protocol and the capability of the weighbridge its difficult to be more specific.

Thanks

Kevin

[former_member703282]

Thanks Kevin for quick response.

I think the protocol to transmit the data will be TCP\IP. If that is the case, as you mentioned I will send a message and receive the response back. I think I can use this methodology to pull data.

I will try this approach

Thanks

Shaji

[former_member204155]

Hi Shaji,

Check this out. Modbus in SAP PCo can help here

https://www.dpstele.com/modbus/rs485-rs232-protocol-data-flow.php