protocolpacket
Member
Kindly advise me if there is any solution to the problems faced by us at site.
The Modbus RTU Master is Johnson’s Control Gateway “ Metasys Integrator”.
This gateway has RS232 Output port
We have connected a RS232-485 converter and have connected 8 AC Drives SK series of Control Techinque to it.
The distance between the Master and the last drive is about 350 Mts.
We are able to communicate with the drives Using “Metasys Integrator”, However the communication is not very stable.
Using Modscan PC based program we tried to analyze the polling results. (http://www.win-tech.com/html/modscan.htm)
The results are as Follows:
Out of 100 polls 20 poll requests results in error, The CRC error is the maximum 80% of the failure and 20% of error we get is Time out.
We have reduced the baud rate to 4800 with no great change in the failure rate.
We do not doubt the cable and the screening.
Question:
----
In master “Metasys Integrator” (Johnson’s Master Gateway) can we program to define failure of value if consecutive 3or 4 poll failures occur then declare the value on the BMS screen as “***** “ .
Johnson’s Metasys Intergrator People always poll a Block of 16 holding register, we have asked them to reduce the Block/ group registers to 5 as only 5 values are required by them per drive. Is it not possible to define in this gateway to make request only for Just 5 Registers instead of always 16 registers per drive loading the buss with useless values.
There are another set of Values that are required from the drive which are not in the consecutive addresses but since we do not know great details of the VCT file that defines the Modbus implementation in Metasys Integrator , we are unable to tell them how to fetch these values. We do not have gret knowledge of Metasys Integrator and its VCT file , can some one help us so that we can indicate the same to the Integrator about his own GATEWAY.
Is there any parameter where we can define the number of retries the master (Gateway) should make before it ensures ***** values appear on the BMS ( SCADA system)?
The Modbus RTU Master is Johnson’s Control Gateway “ Metasys Integrator”.
This gateway has RS232 Output port
We have connected a RS232-485 converter and have connected 8 AC Drives SK series of Control Techinque to it.
The distance between the Master and the last drive is about 350 Mts.
We are able to communicate with the drives Using “Metasys Integrator”, However the communication is not very stable.
Using Modscan PC based program we tried to analyze the polling results. (http://www.win-tech.com/html/modscan.htm)
The results are as Follows:
Out of 100 polls 20 poll requests results in error, The CRC error is the maximum 80% of the failure and 20% of error we get is Time out.
We have reduced the baud rate to 4800 with no great change in the failure rate.
We do not doubt the cable and the screening.
Question:
----
In master “Metasys Integrator” (Johnson’s Master Gateway) can we program to define failure of value if consecutive 3or 4 poll failures occur then declare the value on the BMS screen as “***** “ .
- How do we get rid of the CRC errors
- Could there an issue with the firmware of the Drives ?
- The Drive Manufacturrer specifically states that the RS232-485 converter to be used should be “Amplicon Magic 485F25 or Magic 485F9”
- Any other used converter must have the hardware and software support to tri-state the transmit buffer following the message transmission, Else the drive will not respond.
- We are using “ICP con” 485 converters, this works with other Modbus Integrations well, not sure if this is supporting the so called TRI STATE transmit buffer specifically mentioned by the Drive manufacturer, can any one provide more details?
Johnson’s Metasys Intergrator People always poll a Block of 16 holding register, we have asked them to reduce the Block/ group registers to 5 as only 5 values are required by them per drive. Is it not possible to define in this gateway to make request only for Just 5 Registers instead of always 16 registers per drive loading the buss with useless values.
There are another set of Values that are required from the drive which are not in the consecutive addresses but since we do not know great details of the VCT file that defines the Modbus implementation in Metasys Integrator , we are unable to tell them how to fetch these values. We do not have gret knowledge of Metasys Integrator and its VCT file , can some one help us so that we can indicate the same to the Integrator about his own GATEWAY.
Is there any parameter where we can define the number of retries the master (Gateway) should make before it ensures ***** values appear on the BMS ( SCADA system)?