I used a Hyperterminal to control 9 Watson-Marlow pumps by using RS232. If I have 1 pump turned on and the rest of them turned off, I can read/write messages to the pump. However, if I have two pumps turned on, I can write any messages to both pumps, but I cannot read any messages from neither pump.

Any help is appreciated. Thanks.

 

RS232 is a point-to-point communications method. Using one RS232 port to talk to 9 units would not work too well. You could send data to them ok, but if they are all talking at once, you would not receive any data.

You could use a multiple-RS232 card to communicate with the 9 controllers separately. That should fix your problem.

 

RS-232 is designed for point-to-point communications, meaning from a PC to a device.

I'm surprised that you were even able to successfully connect two devices to a PC. It does not surprise me that you had difficulties communciating when more than one are connected.

If the pumps are addressable, where each pump can be configured with its own address, then you could convert the RS-232 to RS-485 with commercially available converters (one at each pump, one on the PC). RS-485 is designed for 'multidrop', where multiple devices are on the same comm link.

Then your comm 'protocol' would have to include some means of addressing each pump individually.

Actually, I like the multiple RS-232 port idea. There are 8 port PCI cards out there, add the native COM port and there's 9 total COM ports with very little effort.

 

Dear pump user,

This is something that Watson Marlow has only recently become aware of and we have now prepared a beta version software upgrade for this problem and will soon be validating and releasing this software into current production units. If you have multiple pumps using RS232 and you are getting this problem then please contact me for further details on how to obtain an upgrade.
My details are as follows:

Paul Stevens
Aftersales Manager
Watson Marlow Bredel Ltd,
e-mail: [email protected]
tel: +44 (0)1326 370279

 

Ive recently bought a WM 520Du and need to control it remotely, but cant get it to work with hyperterminal or labview. anyone got an idoits guide to the exact operation?

any help is much appreciated.

 

I have the same problem with the same pump too! You can try their in-house software "pumpnet", although it's a quite shabby one. In my case I have to use LabVIEW, but still haven't sorted out how to do it right.

 

Another option to a multi serial port PCI card is a port server. There are several multi serial port servers that connect to the PC via ethernet, then serial to the devices. Software is useally included to allow the software on the PC to access the serial ports as if they were installed on the PC.

 

you need to open up the labview sample "basic write and read". in the upper window replace the command with those provided by WM pump manual. But don't forget add a "\r" after the commands.

Good luck!

 

> you need to open up the labview sample
> "basic write and read". in the upper
> window replace the command with those
> provided by WM pump manual. But don't
> forget add a "\r" after the commands.

I've tried this but still cannot get it to work with LabView or hyper terminal. Any other suggestions would be greatly appreciated.