schmersal Praxi 100, Manual

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Defines how many clients can access the server simultaneously.
The Modbus ‘slave address’ field usually used on Modbus Serial Line is replaced by a single byte ‘Unit Identifier’.
When the TCP is used as the communications protocol, the AC drive is addressed by its IP address and broadcast
messages are not possible. In this case, the unit identifier is useless. In the UDP, it is possible to send broadcast
messages and therefore the unit identifier becomes important.
To keep things simple, the unit identifier is checked when using both TCP and UDP. In TCP you can use value 255 (non-
significant) as a unit identifier and send the messages to all slaves with that value.
For Modbus, this value defines the time in which a message must be received (from Client in Modbus TCP/UDP) before
a fieldbus fault is generated. If timeout is set to zero, no fault is created.
See Chapter 6.3.8.
Table 14. Modbus TCP/UDP Monitoring values
5.3.9 Connection Limit
5.3.10 Unit Identifier Number
5.3.11 Communication Timeout
5.3.12 IDMap IDs
Panel Tree Parameter Range Default ID Description
P5.9.2.2.1.5 Illegal data values 0…65535 - 2453 See 5.2.12
P5.9.2.2.1.6 Slave device busy 0…65535 - 2454 See 5.2.13
P5.9.2.2.1.7
Memory parity
error
0…65535 - 2455 See 5.2.14
P5.9.2.2.1.8 Slave device failure 0…65535 - 2456 See 5.2.15
P5.9.2.2.1.9
Last fault
response
0 - 2457 See 5.2.16
P5.9.2.2.1.10 Control word - hex 2458 See 5.2.17
P5.9.2.2.1.11 Status word - hex 2459 See 5.2.18