# 14.6 IEC 60870-5-104 Slave

Since firmware version 1.8.3, multiple signals with different data types can have the same ioa address.

IEC 60870-5-104 Slave is designed not to lose data acquired from Master protocols. The data that arrives from Master protocols is stored in the cache. This data is checked every second to manage further data sending. The data that leaves IEC 60870-5-104 Slave has output caches. They’re built to provide switching between multiple sessions (redundant SCADA). If a new connection arrives, the old one is dropped, but data, that is stored in a cache, not sent and not confirmed by SCADA is transferred to the new connection. #### Configuring IEC 104 Slave data points To use IEC 60870-5-104 Slave in WCC Lite, it has to be configured via an Excel configuration. This configuration contains two Excel sheets where parameters have to be filled in Devices and Signals. ##### IEC 60870-5-104 Slave parameters for *Devices* tab

Parameter	Type	Description	**Required	Default value (when not specified)	Range
Parameter	Type	Description	**Required	Default value (when not specified)	Min	Max
name	string	User-friendly name for a device	Yes
description	string	Description of a device	No
device\_alias	string	Alphanumeric string to identify a device	Yes
enable	boolean	Enabling/disabling of a device	No	1	0	1
protocol	string	Protocol to be used	Yes		IEC 60870-5-104 slave
asdu\_size	integer	Common address size in bytes	No	2	1	2
time\_sync	boolean	Enable/disable (1 or 0) time synchronization	Yes
port	integer	TCP port	No	2404	0	65535
ioa\_size	integer	Information object address (IOA) size in bytes	No	3	1	3
swt	integer	Send window (SWT)	No	12
rwt	integer	Receive window (RWT)	No	8
cot\_size	integer	Cause of transmission (COT) size in bytes	No	2	1	3
host	string	Space-separated remote host IP addresses (ipv4)	Yes
bind\_address	string	Bind to local IP address (ipv4)	No	0.0.0.0
t1	integer	Acknowledge timeout t1 (sec)	Yes	15	1	255
t2	integer	Connection ACKRSN clock t2 (sec), t2 should be less than t1	Yes	10	1	254
t3	integer	Connection TESTFR clock t3 (sec)	Yes	20	1	172800
message\_size	boolean	The maximum length of a message	Yes	253	0	255
cache\_size	integer	Amount of data to be cached	Yes	100	0	1000
tls	boolean	Enable/disable the use of TLS	No	0	0	1
tls\_local\_certificate	string	Local certificate for TLS connection	Yes (for TLS)
tls\_peer\_certificate	string	Certificate authority file for TLS connection	No
tls\_private\_key	string	A file consisting of the private key for TLS connection	No
command\_timeout\_ms	integer	Time to execute a command before responding negatively.	No	30000	0
command\_age\_ms	integer	The amount of time shift allowed for the command to still be executed.	No	0	0

##### IEC 60870-5-104 Slave parameters for *Signals* tab

Parameter	Type	Description	**Required	Default value (when not specified)	Range
Parameter	Type	Description	**Required	Default value (when not specified)	Min	Max
signal\_name	string	User-friendly signal name	Yes
device\_alias	string	Alphanumeric string to identify a device	Yes
signal\_alias	string	Unique alphanumeric name of the signal to be Yes used	Yes
source\_device\_alias	string	device\_alias of a source device	For commands
source\_signal\_alias	string	signal\_alias of a source signal	For commands
enable	boolean	Enabling/disabling of an individual signal	No	1	0	1
log	integer	Allow signal to be logged. If the log is 0, the signal will not be logged. If the log is more than 0, the signal will be logged	No	0	0	1
gi	boolean	Including/excluding (1 or 0) signals from General Interrogation	No	0	0	1
common\_address	integer	Address of a destination device	Yes
info\_address	integer	Information object address	Yes
data\_type	integer	ASDU type id.	Yes		1, 3, 5, 9, 11, 13, 21, 30, 31, 32, 34, 35, 36, 45, 46, 47, 48, 49, 50, 58, 59, 60, 61, 62, 63
select\_ms	integer	Time limit in milliseconds for command execution. Command selection has to be performed before execution if this parameter is specified. Direct command execution can be performed only if this field is left empty or set to zero.	No	0
periodic\_update\_ms	integer	Signal value is published periodically according to the value set.	No	-	-	-

##### Device status signals

IEC 60870-5-104 has an additional signal which can be configured to show communication status. It indicates if the master device has disconnected from the slave (WCC Lite). To configure such signal for IEC 60870-5-104 protocol, job\_todo and tag\_job\_todo fields with string values are required. For IEC 60870-5-104 slave required parameters for status, the signal will be **signal\_name** **device\_alias, signal\_alias, common\_address, info\_address, data\_type, job\_todo** and **tag\_job\_todo**. Job\_todo value must be *device\_status* and for tag\_job\_todo there are 4 variations: communication\_status, device\_running, device\_error, uknown\_error. Each signal has 4 possible values and is based on the same logic. If the signal returns the value of 0, it means an unknown error has appeared, 1 – device or protocol connection is on and working properly, 2 – device is off or protocol is disconnected, 3 – error or service is down. ### Debugging an IEC 60870-5-104 Slave application If the configuration for IEC 60870-5-104 devices is set up, the handler for the protocol will start automatically. If a configuration is missing parameters or contains errors, the protocol will not start. It is done intentionally to decrease unnecessary memory usage. If IEC 60870-5-104 does not work properly (e.g. no communication between devices, data is corrupted, etc.), a user can launch a debug session from the command-line interface and find out why the link is not functioning properly or use WCC Utility to do that. To launch a debugging session, a user should stop the *iec104-slave* process and run the *iec104-slave* command with respective flags. - Step 1: Service must be stopped by entering the following command into the WCC Lite: **/etc/init.d/iec104-slave stop** - Step 2: After the service is stopped it must be started with the preferred configuration file (JSON files found in /etc/ folder) and a debug level 7: **iec104-slave-c /etc/iec104-slave/0\_0\_0\_0\_502.json -d7;** (0\_0\_0\_0 - bind\_address, 502 - port) - Step 3: Once the problem is diagnosed normal operations can be resumed with the following command: **/etc/init.d/iec107-slave start** ##### IEC 60870-5-104 command-line debugging options ``` -h [ –help ] Display help information

-V [ –version ] Show version

-d Set debugging level

-c [ –config ] Config path

-e [ –redis ] Show redis message ```