Siemens S7-400 installation manual Fitting the Front Connector, Principle of a Coding Key

Wiring the S7-400

4.19Fitting the Front Connector

Principle of a Coding Key

To reduce the risk of a wired front connector being plugged into the wrong type of module after rewiring or module replacement, the signal modules have a coding key for front connectors.

A coding key comprises two parts: one part is permanently connected to the module; the second part is still connected to the first part when delivered (see Figure 4-20).

When you plug in a front connector, the second part of the coding key engages in the connector, becoming detached from the part connected to the signal module. Both parts of the coding key are mating elements and a front connector with the wrong mating element cannot be plugged into this signal module.

Front Connector Coding on the Signal Modules

Shown in the following table is the allocation between the different front connector coding keys and individual signal modules.

Table 4-4	Front connector coding elements
	Signal Modules	Color of Front Connector Coding Key
		red	yellow	green
Digital inputs, outputs
> 60 VDC or > 50 VAC		F
1. Digital inputs, outputs
≤ 60 VDC or ≤ 50 VAC			F
Analog inputs, outputs				F

Plugging In the Front Connector

You can only plug in the connector when the power supply module is installed (lower mounting screw tightened).

!Caution

Modules can be damaged.

If, for example, you plug the front connector of a digital input module into a digital output module, the module can be damaged. If, for example, you plug the front connector of an analog input module into an analog output module, the module can be damaged.

When plugging in the front connector, ensure that the module and front connector are matched.

4-32	Automation System S7-400	Hardware and Installation
		A5E00850741-01