Driver-Specific Parameters
- Last UpdatedDec 17, 2021
- 4 minute read
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UNINTENDED EQUIPMENT OPERATION Do not change these protocol parameters, except on the advice of Technical Support for this product. Failure to follow these instructions can result in death, serious injury, or equipment damage.. |
Note: Always seek the advice of Technical Support personnel for this product regarding undocumented features.
This section describes the SNMPII driver-specific parameters.
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Parameter |
Description |
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[SNMPII]MaxTimeouts |
When SNMP API detected timeout errors exceed this value, DRIVER_UNIT_OFFLINE will be returned by the driver, otherwise DRIVER_TIMEOUT will be returned. Allowable Values: 1 to 3 (requests to SNMP API) Default Value: 1 |
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[SNMPII]SnmpTimeout |
Period in milliseconds to consider an SNMP timeout when using the SNMP API. Timeout is internal to the SNMP API. Allowable Values: 200 to 6000 (ms) Default Value: 1000 You can override the values set for this parameter for a particular device. This would appear in the Citect.INI file as follows: [SNMPII] SnmpTimeOut=1200 Port1.IODev1.SnmpTimeOut=3300 where: Port1 = the port the specified device is connected to IODev1 = the name of the device The above configuration means all devices use an SnmpTimeOut value of 1200mS, except for the device IODev1 on Port1, which will timeout after 3300mS. |
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[SNMPII]SnmpRetry |
Retry count to apply to the SnmpTimeout period before a true timeout is indicated. This then is used by the MaxTimeouts parameter. The count is internal to the SNMP API. Allowable Values: 1 to 5 Default Value: 1 You can override the values set for this parameter for a particular device. This would appear in the Citect.INI file as follows: [SNMPII] SnmpRetry=2 Port1.IODev2.SnmpRetry=3 where: Port1 = the port the specified device is connected to IODev2 = the name of the device The above configuration means all devices use an SnmpRetry value of 2, except for the device IODev2 on Port1, which will retry three times. |
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[SNMPII]PDUGroupOK |
Allowable Values: 0 to disable grouping, or >1 to enable grouping. This specifies the maximum number of SNMP requests which will be grouped into the one packet to the remote SNMP agent. The recommended value is 20, and it cannot exceed 98. Default Value: 20 When PDUGroupOK is 0 or 1, separate SNMP packets need to be generated for each item asked by the I/O server. When non-zero, items in one request from IOServer will be requested in one packet to target device. For more information on setting the PDUGroupOK value, see Setup Tips and Techniques. |
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[SNMPII]ExtraDebug |
Extra debug statements for diagnostic purposes. Debug flags need to be enabled. Allowable Values: 1 or 0 Default Value: 0 |
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[SNMPII]ReturnError |
Used with PDUGroupOK to isolate the variable in a group of tags that is causing an error. When this parameter is set to 1, the driver returns an error when an SNMP packet is returned with an error. When set to 0 (and PDUGroupOK=0), the driver returns either the string "Bad" or the number 2898 (0xBAD). This allows you to see the specific bad variable on your screen. Allowable Values: 1 or 0 Default Value: 1 |
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[SNMPII]UseV2C |
When this parameter is set to 0, it uses SNMP v1.0 and when set to 1, it uses SNMP V2C to communicate with the device. Allowable Values: 1 or 0 Default Value: 0 Note: To configure the parameters at device level, see I/O Device-specific Parameters. |
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[SNMPII]x.y.TestOIDStr (where x is portname, and y is the unitname) |
The SNMPII driver tests the status of each Plant SCADA I/O device by transmitting a request to read the "sysDescr" (.1.3.6.1.2.1.1.1.0) object in the device. TestOIDStr allows alternative OID to be used for testing the status of each Plant SCADA I/O device. An OID needs to end with ".0". If the I/O device is online, it responds by transmitting the requested data. If no response is received, the Plant SCADA I/O device is considered to be offline. Default Value: Test OID string (x.x.x.x.x.0) |
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ChangePorts2000 or EnableChangePorts |
Default 0. Only change if you are on a Win2000/XP/Win2003 Server machine and you want to change the default SNMP port. Default value: 0 or 1 |
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x.y.Port (where x is portname, and y is the unitname) |
Allows the default SNMP port (the default is 161) to be changed. Your SNMP agent needs to be able to listen on the new port number. Default value: Any |
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ComSettingsInInclude |
Default 0, this needs to be set to 1 if the SNMPVARS.DBF information is going to be in Communication Settings in Include projects. Default value: 0 or 1 |
The ReturnError parameter is likely the only parameter you’ll use; the other parameters relate to specialized setups.
When PDUGroupOK is 0 or 1, separate SNMP packets are generated for each item asked by the I/O server. When non-zero, items in one request from the I/O server are requested in one packet to target device.
Note:
1) The target device needs to be able to support large PDU packets if PDUGroupOK is
high. Some devices may exhibit unexpected behaviour if this value is too large.
2) When an error occurs in reading one item in a group, all items are flagged as errors.
To establish which item is causing the error, set PDUGroupOK=1 so that the driver
sends a separate SNMP packet for each item, and set ReturnError =0 so that the driver
does not return an error to the I/O server. Then the item which is causing the problem will be displayed with the value "Bad"
if it a string, or with the value 2989 (the decimal equivalent of the hex 0xBAD) if
numeric. After locating the problem item, remember to set ReturnError back to 1 so
that further errors generate #COM.