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You can find some hints on this site Useful stuff , and an example in Delphi. The PPI protocol is not disclose by Siemens and you will have to dig by yourself. It's easier to use an OPC. Siemens have an OPC for Excel called "S7-200 PC Access", that can save data directly in Excel.
Regards
marie65
This is because your SCR controlled DC will control the tension and current in a loop.
The preset torque will be constant over the entire speed range. It can be set up to maximum value at the base speed or can be set lower then that. If the load torque demand is higher then the preset limit...
How is your simple program build. It just displays something and stop or it send in a loop the same message? If it stop after message is sent, then could be an EMC problem. Did you use 0.1 uF near LCD power supply pins?. Did you try shorten LCD cable ?
marie65
My opinion is to let the 4-20mA as is, convert them at the PC side with your ADC/RS232 and add a 232/232 galvanic isolation to avoid ground loops with your equipment. Is easier to spot and filter the interference on your analog lines then RS485.
You may consider also fiber optic transmission if...
saya plc software
A SCADA system is connected to the PLC using "tags" that are basically memory location found in the PLC and are cyclic read/write. The MODBUS or TCP/IP are only protocols to do this read/write access. The interfaces could be serial (rs485, RS232), ethernet, wireless etc. This...
dc braking
The concept is based on the fact that when you want to stop an ac motor if you inject during the stop phase (AFTER you cut out the ac power) a DC curent trough the coils, the field generated by that current will brake the rotor.
You can find dc injection brake modules produce by many...
touchwin hmi
I don't know what interface have the touchwin device and what protocol use. But on S7-200 the interface is RS485 with gnd on pin 5 line A(Tx/Rx+) on 8 and line B(Tx/Rx-) on 3. The protocol is Siemens propietary PPI or MPI depending on settings. If your HMI have a RS485 interface...
It may be possible to connect the CPU to LCD using 6 transistor (4 data lines and 2 control lines) output line with voltage divider for 5 volts at the LCD side. For LCD control you can check the datasheet of the LCD family from the producer. There, it is explain how to put out the data on the...
ppi cable
The "cheapest" way will be to buy it. In Europe the price for USB version is about 100 Euro. There are some trials to reverse engineer the protocol but there aren't any complete results.
vga disconnect cable
If you have a good (verified) ground connection at both the PC and the monitor you can with minimum risk. Verify if you have any voltage difference between the ground of PC and ground of the monitor when monitor is disconected and both are power on.
RS232 protection problem
Use shielded cable for RS232. The shield should be conected only at an end at the ground. Use the cable as short as possible. Keep away the path of the cable from the high current cables. Check your ground connections for each component of the system (PC, servo drives...
CAN Implementation
First off all, you have to decide for a communication protocol or to create one. The CAN frame is limited to 8 bytes. If you want to transmit from PC, messages with more then 8 bytes then you have to think how the message will be fragmented and pack inside the CAN messages...
25 leds in series
If the led's are in series it means that the same current pass all of them and will lit with the same brightness. You will need a voltage supply bigger then 25 * LED Forward Voltage, that's around 50 volts
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