Conflicts; Protocol Type 3964; Protocol: Modbus-Rtu; Notes - DEUTSCHMANN AUTOMATION UNIGATE CL - DeviceNet Instruction Manual

Deutschmann Automation GmbH & Co. KG

10.3.4 Conflicts

10.3.4.1 Timeout times
The timeout times are preset by the definition of the 3964R protocol and cannot be overwritten !!!
tq = acknowledgement timeout time (2 s).
The acknowledgement timeout time is started after transmission of control character STX. If no
positive acknowledgement arrives within the acknowledgement timeout time, the job is repeated
(max. 2 x). If it has not been possible to complete the job positively after two repetitions, the
high-priority device nevertheless attempts to establish contact with the low-priority partner by
transmitting STX (cycle corresponds to tq).
tz = character timeout time ( 200 ms)
If the 3964 R driver receives data, it monitors arrival of the individual characters within period tz.
If no character is received within the timeout time, the protocol terminates transfer. No
acknowledgement is sent to the coupling partner.
10.3.4.2 Retries
In the event of negative acknowledgement or timeout, a telegram transmitted by the high-priority
user is repeated twice. After this, the gateway signals communication as disturbed but still
attempts to re-establish the connection.
10.3.4.3 Initiation of data communication by the high-priority user
In the case of a negative acknowledgement or timeout, a telegram transmitted by the external
device is repeated twice before a fault is signalled.

10.3.5 Protocol type 3964

The difference to protocol type 3964R is:
1. tq = acknowledge monitoring time
2. The checksum byte BCC is missing.

10.4 Protocol: MODBUS-RTU

10.4.1 Notes

 For reasons of simplicity, "MODBUS-RTU" is referred to as "MODBUS" in the text below.
 The terms "input" and "output" are always viewed from the gateway's point of view,
i.e. fieldbus input data is the data sent by the fieldbus Master to the gateway.

10.4.2 UNIGATE as MODBUS-Master

10.4.2.1 Preparation
Before data exchange is commenced, the parameters "Baud rate", "Parity", "Start bits", "Stop
bits" and "Data bits" and, if applicable, the "Trigger byte" and the "Length byte" must be set.
In addition, a "Response time" which corresponds to the maximum time up to which the Modbus
Slave responds after a request must be set. UNIGATE multiplies the value entered in WINGATE
by 10 ms.
Since the Modbus operates with a variable data format - dependent on the required function and
data length - but since the fieldbus requires a fixed data length, this must be preset via the con-
figuration with WINGATE (blocklength fieldbus input and blocklength fieldbus output). This length
should be selected by the user such that the longest Modbus request resp. response can be pro-
cessed.
29.6.20 UNIGATE
Implemented protocols in UNIGATE® CL with Universal Script
®
fieldbus gateway UNIGATE
®
CL - DeviceNet V. 2.8
™
25