Which voltage values are required when you use a PC/TS/HMI adapter on an arbitrary MPI/PROFIBUS/PPI interface?

Configuration Notes:
Please note that not every type or version of adapter supports all the baud rates that can be set on the relevant MPI/PROFIBUS/PPI interface. More information on this is available in the documentation supplied with the product.

The PC/TS/HMI Adapters of the different generations require different power supply voltages. These voltages are supplied to the adapters via the 9-pin D-SUB socket (where the device connector is slotted). But not all the interfaces of the system supplied the voltage required.

The PC/TS/HMI Adapters require the voltages given below for operation:

• Generation 1 adapters:
  HMI Adapter (order number: 6ES7972-0CA1x-0XA0), PC Adapter (order number: 6ES7972-0CA2x-0XA0) and TS Adapter (order number: 6ES7972-0CA3x-0XA0) require both 5V and 24V at the MPI/DP interface.
  
• Generation 2 adapters:
  The PC Adapter USB (order number: 6ES7972-0CB20-0XA0) only requires 24V at the MPI/DP interface.
  
• The TS Adapters II (order numbers: 6ES7972-0CB35-0XA0 and 6ES7972-0CC35-0XA0) only require 24V as power supply. This 24V supply can come either via the DP/MPI interface or via the supply connector of an external power supply source.

The table shows which interface of the automation system can be connected with which adapter with regard to power supply.

Fig. 1: Table of required/available voltages for the PC/TS/HMI Adapters

1)	Remedy: Use an external power supply.
2)	Remedy: Connect the adapter to a repeater or a CPU 3xx/4xx interface.
3)	Remedy: Connect the adapter to an EM277 or a CPU 3xx/4xx MPI interface.
4)	Remedy: Wire according to the instructions below: It is necessary for connector X121 to be supplied externally with a voltage of 24V. You can make a supply cable for this. A four-wire cable and a 37-pin D-SUB socket are used for this. Fig. 2 shows the wiring for the power supply of connector X121. The two 24V connections and the two ground connections are jumpered on the voltage source side. The MPI/DP interface of the adapter is then connected with connector X121 of the controller. Fig. 2: Wiring of the power supply
5)	Restriction: The "Advanced PPI Protocol" is supported as from PC Adapter USB V1.1 (available since August 2004).
6)	Restriction: It is not possible to load the firmware into a CP via an adapter.
7)	Restriction: The adapters do not support any PROFIBUS address assignment.
8)	The following power supplies are available with the modules: IM151-7 (CPU) 5V and 24V IM151-1 (without CPU) only 5V.

Note:
The RS232 interface has the following permissible voltage ranges:

• At logic level "0" the voltage level is between +3V and +15V.
• At logic level "1" the voltage level is between -3V and -15V.

If, for example, you use a voltage level of 4V, this is still in the permissible range, but is very close to the limit of the undefined range. Now, if there is power attenuation or very high EMC interference, the result might be that the signal is no longer clearly recognized and after multiple transfer attempts there is a negative acknowledgment of the message. Since the SIMATIC products are designed for industrial application, the voltage values are in the upper range so that there is no interruption in the transfer. More information is available in the Internet in our FAQ "Technical data of the RS232C interface" in Entry ID: 2892960 .