读取VISA中返回错误

我试图通过labview读取Lightwave Compnent Analyzer（LCAN 4376B，与PNA N5242A连接）的端口数据，使用以下语法写入和读取VISA函数：MMEM：STOR：TRAC：FORM：SNP RI FORM：DATA ASCII，0
CALC1：数据：SNP：PORTs？
“1,2”但它在读取VISA中返回错误。
错误代码：-1073807339，超时操作命令之前已过期。
我想知道这是否是LCA的问题。
我使用纯PNA（N5247A）测试了相同的语法，并可以在读缓冲区中获取测量数据。
任何人都可以帮我配置问题吗？
还有用于LCA的SCPI命令的参考手册吗？
在网站上找不到它。
谢谢。



     以下为原文

  I am trying to read the port data of Lightwave Compnent Analyzer (LCAN 4376B, connected together with PNA N5242A) by Labview write and read VISA function with the following syntax:

MMEM: STOR: TRAC: FORM: SNP RI
FORM: DATA ASCII,0
CALC1: DATA: SNP: PORTs? "1,2"

But it returns error in read VISA. Error Code: -1073807339, Timeout Expired before operation command.  

I am wondering whether it is the problem of LCA. I tested the same syntax with pure PNA (N5247A) and can get the measurement data in read buffer.  

Could anyone help me to configure the problem?  

Also is there any reference manual of the SCPI commands for LCA? Cannot find it in the website.  

Thanks.