Has always been a half a bucket of water technician, for many years, frequent transition reasons, what have learned a little, what all don't proficient, , in recent years the company has a walk the modbus network system of dc motor, is 485 through the network to control dc motor actually do some simple forward reverse action, at the same time some state feedback,
Structural design of a floor there is a project, as shown in figure, each floor in the two groups 485, construction of north and south side, about 30 meters, the farthest distance rate of 485 to 9600,
Known issue: the project is made of early, according to the development of this system was half a bucket of water, the guidance of the Hong Kong guy think distance is short, node and less, so don't go doing very heart
1, network topology, no strict holding hands, a city's bus is probably more than 20 meters, about four or five meters, each branch line and individual nodes because access port changed position increases the distance,
2, power with the three, two of the same brand and specifications about 27.9 V, a different brand different specifications about 26 V, 0 V lower than the other two power supply is also about 2 V,

In recent years is in the graph on the right side of the equipment (single power supply) has always been very normal, there is almost no miss, often the problem can't unicom on the left side of the equipment, even after the resumption of normal soon began to trouble,

Before the user use very little also calculate, have recently begun to use frequently, fault become can't avoid, under the guidance of the Hong Kong guy, doubt power problem these days made several lines,
1, the original device on the electricity, there is a 3 and a half hours after the error and hot near the 485 chip, another up, the beginning is normal, but it didn't take long and the same situation,
2, the three power of 0 v and connect together, the results lost in large area, failure,
3, taking down the 26 V the power source, its original take on four groups of power by the other two 27.9 V power supply share, at first the original normal 8-14 completely lost, after and 0 V is normal, but 6 or make a mistake, it didn't take long 1, 4 error, failure,
3, keep the 26 v power supply, originally a Shared by two other power supply power supply on the four groups of one of the power supply, there is a 6 errors, still observe the follow-up situation,
As shown,




Thank you for your guidance for sure,

CodePudding user response:

1, hot chip, check each terminal have resistance, only as far as a terminal resistance line,
2, check for leakage,
3, the merger of 0 v should not have too big effect, check the specific circuit of voltage,

CodePudding user response:

reference 1st floor hhhh63 response:

1, hot chip, check each terminal resistance is there, just keep a terminal resistance as far as,
2, check for leakage,
3, the merger of 0 v should not have too big effect, check the specific circuit of voltage,

Thank you, in fact, in the second figure, because change the power led to a set of all lost, originally is stable later resumed normal 0 v and connect together, measuring OV of two power supply, a pressure difference about 2 v, my guess is that this could be the cause,
By the way of understanding the whole system did not end resistance, because the wiring is not standard, the main line is not long (about 30 meters), instead of the bifurcated 5-10 meters long, so this time I will consider to add termination resistors, whether should add at the end of the line end last bifurcation, or should find the longest one end of a fork?

The leakage situation, you mean a 220 v leakage? I will measure again carefully,

This is going to hold a oscilloscope in the past, actually how also don't know,

CodePudding user response:

refer to the second floor weixin_46510462 response:

Quote: refer to 1st floor hhhh63 response:

1, hot chip, check each terminal have resistance, only as far as a terminal resistance line,
2, check for leakage,
3, the merger of 0 v should not have too big effect, check the specific circuit of voltage,

Thank you, in fact, in the second figure, because change the power led to a set of all lost, originally is stable later resumed normal 0 v and connect together, measuring OV of two power supply, a pressure difference about 2 v, my guess is that this could be the cause,
By the way of understanding the whole system did not end resistance, because the wiring is not standard, the main line is not long (about 30 meters), instead of the bifurcated 5-10 meters long, so this time I will consider to add termination resistors, whether should add at the end of the line end last bifurcation, or should find the longest one end of a fork?

The leakage situation, you mean a 220 v leakage? I will measure again carefully,

This is going to hold a oscilloscope in the past, actually how also don't know,

Said is wrong, when the third figure parallel 0 v, two power 0 v differential pressure about 2 v,

CodePudding user response:

More than 10 meters, interfere with the heavy to add resistance, total resistance cannot be less than 60's

CodePudding user response:

Look at when you were A 485 bus into each terminal thermal protection, model selection is what, don't protect the resistance cannot too big, whether there is A transient protection, check whether the failure, on the bus A connected resistance, B for resistance, bus terminal and A terminal connected, my ball ball 36351109485 have nearly 20 years,

CodePudding user response:

reference 5 floor weixin_44087732 reply:

look at when you were A 485 bus into each terminal thermal protection, model selection is what, don't protect the resistance cannot too big, whether there is A transient protection, check whether the failure, on the bus A connected resistance, B for resistance, bus terminal and A terminal connected, my ball ball 36351109485 have nearly 20 years,

Just ask to develop this plate, pull resistance inside the board have already made up and down, continue to test tomorrow, going to do with an oscilloscope contrast, hope to have the result, just added you WeChat

CodePudding user response:

Yesterday went to a day,
First is a set of 485 with a power supply, power supply does not cross use, although the two power difference a bit big, different voltage, 0 v is different also, but by two groups of 485 separate and isolated access gateway hope can avoid their power differential pressure problem,
In the process of test, found that some terminal current situation to 0 v A has about 3 v, some terminal voltage, but regardless of the voltage, pick up at the time of the bus can be normal unicom, don't know what is the reason is not stable, so I will be no line 3 v board replace,
After this operation improvements (started to go wrong on the electricity for a few minutes, before the watch more than an hour ok)
Broke again a board the next day, when it is accidentally, in a piece of good went up again to observe,

Now in the mind a bit uneasy, if this didn't solve the problem, they do not have what idea, although the two power differences, but the two ends of the power supply management two parts respectively, two groups of 485 is to together through isolation,
Considering the hardware design is not considerate, namely again, itself is flawed,

CodePudding user response:

Find someone to write program of the hardware is stc12c5024ad hardware, 2 slices ready with 22.1184 crystals with hc244 do 12 road input a 64 - bit dial the code switch do address input 4 tpic6b595 2 set of output a 485 and Siemens plc200 do credit to PLC program written 12 road by n address input count alarm display

CodePudding user response:

The power of the change on the left side of the power supply to the right specifications