Commands
2014-
02
43
7.8.7
Heartbeat and ident status
If you select instance 112d and 162d of the assembly object, the size of the output field is 0
bytes and the size of the input field is 10 bytes. The status and the reply counter are included.
The advantage of this procedure is that only a few bytes are transferred via the bus.
Identification commands are transferred to the control unit as explicit commands. A new ident
response can be read as soon as the value on the reply counter changes.
7.8.8
Data hold time
The data hold time indicates how long the responses from the control unit remain in the input
field. Set the data hold time via the boot-up object or on the device website. Select values
between 0 and 2.55 seconds in 10 ms increments. The default value is 100 ms. The PLC must
read the response before a new response is written so that no responses are lost. Ensure that
the data hold time is greater than the maximum cycle time of the whole system (including data
storage to the PLC). Do not select a data hold time with a value excessive to requirements
because
■
the reaction time of the device will increase if several responses arrive in quick
succession.
■
The maximum possible number of response telegrams per time unit decreases when the
data hold time is increased. A memory overflow may occur. The PWR/ERR LED flashes
green.
Sepa-
rated
mode
104d
154d
x
x
x
105d
155d
x
x
x
106d
156d
x
x
x
107d
157d
x
x
x
108d
158d
x
x
x
x
109d
159d
x
x
x
x
110d
160d
x
x
x
x
111d
161d
x
x
x
x
112d
162d
x
Implicit data
exchange
Explicit access
Instances from input/output commands
Output
instance
Input
instance
1
2
5
(conf.)
6
Byte status
Description
00
Status of the IDENTControl
01
Reply counter of the IDENTControl
02
Status of channel 1
03
Reply counter from channel 1
04
Status of channel 2
05
Reply counter from channel 2
06
Reserved
07
Reserved
08
Reserved
09
Reserved
