How do I solve "-307" error on ZKTeco SDK?

Hello everyone and thanks for reading this problem.

I have a solution in C# using the zkemkeeper dll to get the records from some access control devices. When I "ping" them, there isn't any problem, but when I try to connect to them (Using my solution or the standalone demo to get attendance) I get the "-307" error with the "Unable to connect message". That's not very clear and I would really aprecciate if someone can explain what this error is (please!!!!). I would really like to understand these errors myself, so, where can I find all the definition of these errors?

In short:

1.- What is the problem regarding the "-307" error? 2.- Is there any place where all these errors are documented?

Thanks in advance!!

Attention The dwErrorCode parameter specifies the error code. The values are described as follows:

1. During connection, the following error codes may be returned: 0 Connected successfully -1 Failed to invoke the interface -2 Failed to initialize -3 Failed to initialize parameters -5 Data mode read error -6 Wrong password -7 Reply error -8 Receive timeout -307 Connection timeout In invoking other interfaces, the following error codes may be returned: -201 Device is busy -199 New Mode -103 device send back error of face version error -102 face template version error, like 8.0 face template send to 7.0 device -101 malloc memory failed -100 Not supported or the data does not exist -10 The length of transmitted data is incorrect -5 Data already exists -4 Insufficient space -3 Wrong size -2 File read/write error -1 The SDK is not initialized and needs to be reconnected 0 Data not found or duplicate data 1 Correct operation 4 Parameter error 101 Buffer allocation error 102 repeat invoking
2. Underlying error codes: -12001 Socket creation timeout (connection timeout) -12002 Insufficient memory -12003 Wrong Socket version -12004 Not TCP protocol -12005 Waiting timeout -12006 Data transmission timeout -12007 Data reading timeout -12008 Failed to read Socket -13009 Waiting event error -13010 Exceeded retry attempts -13011 Wrong reply ID -13012 Checksum error -13013 Waiting event timeout -13014 DIRTY_DATA -13015 Buffer size too small -13016 Wrong data length -13017 Invalid data read1 -13018 Invalid data read2 -13019 Invalid data read3 -13020 Data loss -13021 Memory initialization error -15001 Invoking return value of status key issued by SetShortkey interface repeatedly -15002 Invoking return value of description issued by SetShortkey interface repeatedly -15003 The two level menu is not opened in the device, and the data need not be issued
3. getdevicedata and setdevicedata invocation error codes -15100 Error occurs in obtaining table structure -15101 The condition field does not exist in the table structure -15102 Inconsistency in the total number of fields -15103 Inconsistency in sorting fields -15104 Memory allocation error -15105 Data parsing error -15106 Data overflow as the transmitted data exceeds 4M -15108 Invalid options -15113 Data parsing error: table ID not found -15114 A data exception is returned as the number of fields is smaller than or equal to 0 -15115 A data exception is returned as the total number of table fields is inconsistent with the total number of fields of the data
4. Firmware error codes: 2000 Return OK to execute -2001 Return Fail to execute command -2002 Return Data -2003 Regstered event occorred -2004 Return REPEAT Command -2005 Return UNAUTH Command 0xffff Return Unknown Command -4999 Device parameter read error -4998 Device parameter write error -4997 The length of the data sent by the software to the device is incorrect 228 229 -4996 A parameter error exists in the data sent by the software to the device -4995 Failed to add data to the database -4994 Failed to update the database -4993 Failed to read data from the database -4992 Failed to delete data in the database -4991 Data not found in the database -4990 The data amount in the database reaches the limit -4989 Failed to allocate memory to a session -4988 Insufficient space in the memory allocated to a session -4987 The memory allocated to a session overflows -4986 File does not exist -4985 File read failure -4984 File write failure -4983 Failed to calculate the hash value -4982 Failed to allocate memory Note This interface is applicable to the new architecture firmware.