CP341 MODBUS RS485 RTU双线通信问题CP341 MODBUS RS485 RTU two wire communication problem

你好

Hi,

我的西门子系统是STEP 7 V8.0，CP341是6ES7-1CH02-0AE0。从机侧是消防泵本地控制器。

My Siemens system is STEP 7 V8.0 and CP341 is 6ES7-1CH02-0AE0. The slave side is a fire pump local controller.

我已经配置了CP341和相关逻辑。下载后，我发现TXD是唯一闪烁的指示灯。

I have configured CP341 and related logic. After my downloading I found the TXD is the only light flashing.

我通过检查两条线路开始故障排除。请参阅下面的步骤：

I started troubleshooting by checking the two wiring. See my steps below:

1、我从CP341侧拔下通信电缆，TXD仍然是唯一闪烁的。基本上没有什么变化。

1, I unpluged the communication cable from the CP341 side, the TXD was still the only one flashing. Basically nothing changed.

2，我用万用表测量了针脚4和11，那里几乎没有电压。

2, I measured pin 4 and 11 with a multimeter and there was almost no voltage there.

3、我去消防泵控制器处测量两线电压，几乎什么也没得到。

3, I went to the fire pump controller and measured the two wire voltage and got almost nothing.

请参阅随附的照片副本。在消防泵手册上，它显示使用引脚2和7，但没有显示奇偶性。

Please see the photo copy attached. On the fire pump manual it shows to use pin 2 and 7 but it doesn't show the parity.

我的问题是：

My questions are:

1、根据消防泵的手册，西门子方面应该是引脚3和引脚8。对我来说，这是错误的。销应为4和11。

1, According to the manual from fire pump Siemens side should be Pin 3 and 8. To me it is wrong. The pins should be 4 and 11.

2，如果我测量消防泵控制器上的针脚2和7，应该会显示一些电压，如5V，对吗？我怀疑泵侧未正确配置为激活RS485端口。

2, It should show some voltage like 5V if I measure pin 2 and 7 on fire pump controller, right? I am suspecting the pump side is not properly configured to active the RS485 port.

当做

Regards

特里斯坦

Tristan

你好

Hello,

由于平衡通信系统，也许最好用示波器检查一下。在另一种情况下，CP341上的LED照明也取决于消息的长度，而不是明亮的灯光。将PC连接到PLC CP 341，而不是将实际设备连接到PLC CP341，当然，使用合适的转换器（USB/串行端口232或485）进行简单测试，并运行一些串行终端应用程序（在许多情况下，超级终端就足够了）。检查您的PC应用程序中来自CP341的输入消息，它们的正确结构符合您定义的标准。检查后，您将处于正确的起始位置，以进行真正的从属设备测试。

due ballanced comm system, maybe better check that with osciloscope. In other case, lighting of LED on CP341 also depended to long of message, shorter message - not bright light. Make simple test with PC connected instead of real device to PLC CP 341, of course with suitable converter (USB/Serial port 232 or 485) and run some serial terminal application (Hyperterminal will be enough in many cases). Check incomming messages from CP341 in your PC application, their proper structure due your defined criteria. After check this, you will be in right start position for real Slave device testing.