Samson 4785, Mounting And Operating Instructions

Page: 68 / 78

9.2 "CHECK_BACK" messages
Bit
no.
Name Description
R = static message, remains valid while the error is present in the field device
A = dynamic message, automatically reset when read
0 CB_FA IL_SA VE Fail-safe position
The fail-safe position was activated by the device, either by selecting operating
mode "OUT OF SERVICE", by activating the forced venting function, or by a
communication failure.
The device switches to "OUT OF SERVICE" mode.
R
1 CB_REQ_LOC_OP
Request for local operation
Set when local operation was requested, but not enabled (LOCAL_OP_ENA = 0).
A
2 CB_LOC_OP Local operation R
3 CB_OVERRIDE
Emergency operation / forced venting active
Forced venting was activated, i.e. the signal applied to ter81 and –82 is
smaller than 3 V. The control valve moves to fail-safe position regardless of the
control loop.
Automatically reset when a 6 to 24 V DC signal is applied to ter81 and –82.
R
6 CB_ZERO_ERR Zero point error
Displayed when "manufacturer specific" was set for "Selection identification
number". Message indicated by bit 8 of the DIAGNOSIS parameter, see section 9.3.
7 CB_TRAV_TIME Status of travel monitoring
Set when permissible transit time was exceeded.
A
10 CB_UPDATE_EVT Change of static data
Set when device data are changed. Enables monitoring of
(unintentional/unauthorized) changes of the initially adjusted values.
A
11 CB_SIMULATE Simulation mode , i.e. values are not derived from the process.
Set when the device is in simulation mode. In this case, the controlled variable x is
predetermined.
R
13 CB_CONTR_ERR Internal control loop error
Displayed when the positioner is unable to control the adjusted range of tolerance
for error messages within the preset delay time.
Possible sources of error:
– Oscillation caused by actuator operated too rapidly (small travel volume)
Remedy: Reduce supply air pressure as described in section 3.1.2 or install a
signal pressure throttle.
– Supply air failure/insufficient supply air – Filter is clogged
– Solenoid valves are oiled – Actuator diaphragm is ruptured
– Actuator springs are broken – Control valve is blocked
– Considerable increase in friction at the control valve
Message is indicated by bit 7 and bit 13 of the CHECK_BACK parameter (see table
on pages 42/43).
Status of bit 7 is reset automatically. Bit 13 is reset via "SELF_CALIB_CMD = 10"
(resetting ’control loop error’)
R
68
EB 8382-2 EN
Messages and diagnosis