Can any one solve my problem regarding RS232 & RS485?

Why u use RS485 intially to transmit the data?

Pl. use RS232 which can work up to 30 mtr easily.

Tryout the suggested.

Dhananjay

He is using that bus because he has many slaves on same RS232C port. He has no way to control their communication and they perhaps are killing the communication. He may also be sending non-printable control characters that may be triggering the computer. Another problem may be the hardware handshake which he might have not disabled.

Try putting one remote and a computer. Do you get data in HyperTerminal Program? For HandShake set it to none, data 8, bit, no, parity. Transmit only printable ASCII chars and not all ASCII 00H to 0FFH. or numbers 0-255. Limit to char that you can see.

Sir,

i've one remote computer, There is Elcotrol Meters Softwear its us to collect data from each meter, 8 bit data, ASII chars, bud rate 9600 diffret address on each meter 001-016,i try to fixed on start & end of meter with 120 Ohms resistor parallel, all wiring checked + to + and - to - on each meter. and commuication cable is twisted three core shielded, and shield connect to earth. I saw ALLEN-BRALEY Bulleti 1400c RS232C to RS 485 Converter, at there they use two 150 Ohm resistor same as I use from start & end. And pin 1 of RS232C connected to shield, pin 1 of RS232C connected to earthig of Computer.

But hanging comes every day or some time day after tommarow.

Make sure you ground only one end of the shield.Grounding both ends will create noise rather than shielding from it.

we use RS485C because of log distance & meters have RS485C communication option only, RS232 will not work at 50 - 250 meter, you need to check distance for each communication. please to see distance.

You should be using a low-capacitance wire, (below 12 picofarad per foot) Long distances and multiple shileded wire usually exhibit high capacitance values which can attetnuate your signals.

Dear Friend,

When Communicating on Mutidrop Busses, Pls follow this practice

1. 120 Ohm Resistor at the source and Destination Station (The Starting Station and ending stations Physically)

2. Pull Up of 1K Ohms at the Starting station.

3. Other stations should not have terminating resistors or Pull Ups or Pull Downs.

If Problem Persists pls feel free to contact Sandeep Patalay 09848315940.

Rgds,

Sandeep Patalay.

Team Leader

HBL Power Systems Ltd.

What type of 485 to 232 converter are you using, I have found that some require an external power supply to power the 485 side. Try to look for any loose wiring. Also try to check the modbus address and make sure that any other slaves do not have that the address, check the baud rate, data bits, parity, stop bit and flow control. i would also follow Shyam idea this is the best way to trouble shoot RS communications.

Hi

I like to use a Port-Powered Rs -485 converter from B&B electronics. It is Model #485SD9TB. For your application it would require an external power supply

June

First check your main communication module if it supports half-duplex or full-duplex then your RS-485 to RS-232 converter has to be configured to suit this requirement. I did use Weidmuller converter, which is configurable for half or full, and it works very good.

its half-duplex type, and protectio key spacially for softwear installed at printer port. from manufacture made, With out key softwear is not make schudle & grenate massege for key installation required.