ENGLISH 7/8
MI002875-E
After a time interval of about 1 minute, the timeout message on the slave devices actually
belonging to the network disappears, returning to the normal functioning.The behavior just
described can be observed if there is the absence of the Z-LINK1 device connected to the
interested Modbus slave device, too (for example, the previous Z-LINK1 connected to the Z-
4AI via local bus).
Infact
the Z-LINK1 devices can detect network paths with timing usually much higher
than the timeout of the Modbus Master.
Therefore, the PC (Modbus master) continuing to
poll, but the network is still employed to locate the device no longer connected. In particular,
the requests that arrive to the network when it is employed by another request will be
discarded, causing the subsequent failure on the slaves in the list (timeout temporary).
Use of the network
To use the devices in the best way, mind the following points:
1. All RS485 buses headed by a Z-LINK1 must be properly polarized and terminated.
2. The packet sending for Modbus broadcast (Modbus address 0x00) is supported by the
network; anyway, for multihop MESH topologies, it is strongly discouraged because it
involves long communication times and low reliability of achieving all network elements.
3. For networks constituted by a large number of devices, avoid the densification of
infrastructural elements within the same covering range.
Important points:
- Only for the Z-LINK1 configured in REMOTE I/O modality as master, the max number of
input/output that can be configured in the I/O repetition map:
* is 20, for digital inputs/outputs
* is 50, for analog inputs/outputs
- The Easy setup software allows to negate the status of digital outputs, compared with the
corresponding input; allows to scale the analog inputs, repeating the values in the
corresponding analog outputs. In both cases, it is possible to set the fail conditions.
- It is advisable to connect the (digital or analog) outputs in the Modbus master local bus
- At the first start, the master module checks which slaves belong to the network effectively.
For this reason: first, power on the Z-LINK1 «slave» devices; final, power on the Z-LINK1
«master» module
- In the Easy Setup software (in Test configuration window) there is a incremental counter, to
display eventual fails in the modules connected and the radio communication quality. In
correspondence of each module of displayed I/O map, there is a flag that signals eventual I/O
fails in reading/writing.
PC
(master)
Z-LINK1
(SW1-1
=on)
bus RS485
Z-4AI
Z-LINK1
(SW1-1
=off)
bus RS485
Z-8TC
Z-LINK1
(SW1-1
=off)
bus RS485
timeout
timeout
(temporary)
